iPad Mini 2021
The iPad virtually no one should buy. Though technically impressive and at least in Apple-world 'reasonably' priced.
This is a wonderfully portable device, but it seems like typically another iPad is going to be better. The small screen is worse for basically everything that you might want to do on an iPad from surfing the web to watching video, let alone more serious creative uses.
Probably you should go with a 'regular' sized iPad (screen 10-11 inches). For value the regular iPad, for balance the Air or if you have the money the Pro (the M1 is ludicrous and fast refresh rate screen is great). I'd suggest avoiding the 12.9 inch one as it is unwieldy and the marginal utility from increase in screen size is minor (the price increase is not).
Where the iPad Mini is actually great (and this was why I got it) is as a test device for development. Making sure your App works on this small screen will make it robust. And the small size is convenient for storage/taking up less desk space. The portability is also nice for commuting etc, but if you have a bag for a laptop you can probably fit a full iPad in anyway.
On writing reviews
I think it is worthwhile reviewing things, as Socrates maybe said "the unexamined life is not worth living". Here I share some reviews that I think are of general interest. I try to keep things short and focused on what seems like the less obvious aspects. But I write many, many more using an app I made Micro Reviews. Using this app I capture reviews of all sorts of things, like books, films, TV, food, drinks, coffee and more. These reviews are largely intended to be private, notes to my future self. This guides future purchases and serves as a journal of experiences.
Micro Reviews uses Apple's iCloud to allow for data sync between devices, yet making sure your data remains private (unlike in many Apps the developer, in this case me, can never see it). With tags and categories you can keep your reviews organised. You can also search your reviews and export them to a CSV file (so you do things with the data in Excel).
Download Micro Reviews for iPhone, iPad and MacOS. (It is free!)
You can also learn more about Micro Reviews but why not just download it (it is free and a small install size).