There isn't much you can do on a tiny smart phone anyway due to its size and availability of apps. Tablet-optimized apps are superior, offer far better user-experience and more usable than mobile apps or scaled-up mobile apps. Further, some of the best apps such as Cubasis, Gadget, iMS-20, Magellan, Procreate, etc. are developed ONLYfor the iPad. Also learn why Procreate refused to create an Android version of their tablet app. My technique is to use the latest and the greatest iPad and keep the phone outdated. In other words, I buy a new iPad when I run out of room or when it becomes too slow or when the current iOS/hardware does not support the newer apps made for the newer iOS/hardware - or every 3-4 years. I consider a smart phone is good for just making calls, checking email, weather, calendar, texting, photos, etc - that's all - which is why I have a 128 GB AT&T Cellular iPad Air 2 but still have a 5-year old 32 GB iPhone 4 and don't plan on upgrading it any time soon. Go for a tablet.
If the above is not convincing enough, I'll give you 2 more bigger reasons to go for a tablet (iPad):
Spotify which is the BEST music streaming service is FREE on desktops/laptops and tablets (on-demand) - you can play any song at any time. It is free on smartphones as well but it it is shuffle-based which means it plays random songs from the album (not on-demand). Spotify has over 30+ million songs in every language covering every country. Other good streaming services are Google Music All Access, Pandora & iTunes Radio.
DJay 2 app is integrated with Spotify - you don't need a music collection to mix like a Pro-DJ and amuse others.
iOS, Android or Windows tablet?
It all boils down to who was the pioneer in the game with more apps. It is analogous to traffic to a website - most websites are alive today because of their traffic due to being the pioneers and most of them would not have been as successful as they are if they were launched now. Apple started the apps, AppStore, smart phones, tablets (well, they improvised the competing products, made them better and more usable). Consequently, the iOS AppStore has more than a million apps and the most tablet-optimized apps giving you that unique tablet-experience as opposed to scaled-up mobile apps you find on Android. Most developers create the iOS version of their apps first before considering porting them to other platforms. Some developers refuse to create Android versions of their apps and some developers quit making apps for Windows saying, "You cannot make money on Windows apps". iOS has the most number of tablet-optimized apps, family-sharing of apps, etc. Android has fewer tablet-optimized apps and fragmentation issues, malware, latency issues from being one-size-fits-all bloat-ware, open-source model and not all users get the latest and greatest due to being at the mercy of several vendors. Well, whatever - I'm not starting a war. You get what you pay for. When you want to accomplish something and you found a perfect app for that, you have found your platform. Go for iOS - if you can.
iPad Air or iPad mini?
I simply loved the mini when I had one for 2 years - it is a small wonder and always went wherever I went. Before the mini, I had an iPad 2 and it always used to stay home because of its heft. I got the MOST use out of the mini. Mini was PERFECT for everything - email, browsing, watching videos, playing games, reading books, etc - I never had any issues with any of these activities because the apps made for the bigger iPad work the exact, same way on the mini without any changes and they give you the same full tablet-experience unlike the scaled-up mobile apps we find on Android. However, I found that the keyboard on the software musical instruments in the DAW apps I use was a bit tiny for my adult fingers and had issues playing faster without making hiccups. Finally, when I purchased a much lighter iPad Air 2, it was a BLISS - the issues of keyboard size and playing software instruments was gone, gone! I can still carry my new iPad Air everywhere because of it its light weight and also due to its side bezels that were trimmed by Apple making it less wide - all these changes made the difference in size between the full size iPad and the mini negligible. What the heck? Apple even made iPad Air 2 thinner than iPhone 6 !! Honestly, I still like themini as it fits in my jacket pocket - not so much with the full-size iPad Air. So, here is my suggestion - if you are an adult and wanna play DAW apps, just buy the full-size iPad - preferably the Black one. If not into music or if you are a kid, go for the mini. Mini is such a PERFECT match for kids!!
Black iPad or White iPad?
Black iPad gives an immersive experience while watching videos, playing games, etc as its black sides/bezels blend with the black background of the app/game. If you are into playing games or watching videos, go for the Black iPad. Black iPad is recommended if you intend to use music/DAW apps as well. A black leather case does not fade or discolor.
White iPad blends with the background color of browser, web sites, books and productivity tools such as email, calendar, word processors, spreadsheets, presentations, etc. Having a black border for apps that have a white theme is a bit of a distraction. If you wanna use the iPad just for productivity tools/apps, reading, browsing, etc go for the White iPad. Light-colored leather cases fade or discolor over a period of time.
HINT: Get a black face-plated iPad and a white face-plated iPhone (you use iPhone mostly for productivity tools, right - that have white themes?)
Cellular or Wi-Fi edition?
Cellular edition sets you off by about $130. If you plan on getting a data plan for your iPad, always go for theCellular edition because it costs just $10 a month to add it as a device to your data plan. Remember, it costs $30 a month to add a Wi-Fi iPad to a data plan. So the extra cost of $130 pays for itself in about 6 months and after that it is a savings of $20 every month. Cellular edition is a teeny bit heavier (by a few grams) and the battery drains a bit faster when you add a data plan to it (just like an iPhone with a plan). However, iPad Air works with a blazing performance and has such a great battery - it lasts for days on a single charge even with a data plan on it.
AT&T, Verizon or other carriers?
AT&T hands down - I found their network, coverage, signal strength and reception far superior to outdated technologies/networks other carriers use. With Verizon and other carriers, you enjoy their latest technologies only in some areas and once you are out of those areas, you are back on their outdated, 3G or even inferior networks. Plus, AT&T's customer service is FANATIC!!
Since iPad does not come with external storage, more is always better. 16 GB is long-outdated and maybe OK for folks who use it for just productivity tools (remember, White iPad?). You should go for a minimum of 32 GB. If you are a gamer or deal with lots of apps, music files, photos, videos, etc, you should go for the maximum storage. Apple products can be used for at least 5-10 years or more without issues (I still use a 5-year old iPhone without any issues but I have the latest iPad) and they have a good resale value and so, cost should not be your concern. You buy it, you use it, you enjoy it - you get returns out of it! So simple. The last thing you want is run out of room and repent for not having bought more storage. Do not skimp on storage capacity. I found the iPad Air 2 with 2 GB RAM is blazing fast even with the latest, memory-hungry, badly written apps (such as Auria) that use humungous resources.
HINT: If you want to buy both iPad and an iPhone, consider buying a White/Rose-Gold iPhone (for productivity apps) and a Black/Space-Gray iPad (for apps, games, video watching, etc).
If you plan on buying auxiliary items such as microphone, keyboard, etc - buy the ones that connect to your tablet through the power socket and not through headphone jack because the ones that connect through the power socket offer full features, quality and power compared to the ones that connect through headphone jack. Always buy Apple peripherals, kits, etc because 3rd-party stuff does not work properly and renders inferior output.
Eg: Camera Connection Kit - buy the Apple brand and you'll have not issues with it.