Preamble...

By popular demand, I have compiled here a list of likes, dislikes, frustrations (and a few tips) about art apps I've tried for the ipad. Please note that these kinds of things change fast, so I'll note the date: December 2020. And they are only my opinions.
But first, so you know, my equipment:
I splurged and got myself a top-of-the-line ipad PRO, and the latest apple pencil. The pro is the biggest ipad, and I have to admit I like all the space! If I'm drawing from a reference, I can have both the reference and the drawing on the screen at the same time, nice and big. Also the pencil attaches (and charges) magnetically, which is handy. My stepdaughter has the smaller ipad AIR, and an older pencil, and while the air is just as good, it is smaller, and the old pencil must be attached in an awkward way, and doesn't seem to hold a charge for as long.
CASE: I bought
this case for my ipad, which allows me to prop it up in a couple of different orientations, or open it fully like a book. It also protects the screen when it's closed. Note: you'll need a case that fits YOUR ipad.
SCREEN PROTECTOR: Also, I bought a very inexpensive
MATTE screen protector that makes drawing with the pencil FEEL more like drawing on paper. Because I found it very awkward to draw straight on the glass.
LEARNING THE APPS: As for the apps, I learned how to use them by just trying them out. I touched every single thing on every menu until I was familiar with what happened when I did. I tried out every tool, with as many colors and adjustments as I could think of. You won’t break the apps! I promise. No matter how hard you try.
TUTORIALS: But there are also a billion tutorials about each one on
youtube. The trick is finding a presenter whose voice doesn’t grate on you. : ) Then if you have specific questions or problems, good ol’
google usually has the answer.
(update) COST OF APPS: I once paid $700 for the desktop version of Photoshop, and now pay $9.99/mo, so compared to that, all the art apps for ipad are super cheap!!! I can't remember exactly how much I paid for each one (and now that I've paid the prices don't show anymore), but they are all under $15, and usually a one-time fee. Some you get for free (or very low cost) but have to pay a little more to use ALL the features. The great thing about that is you can try out the app first and make sure you like it before you pay.
(update) SPLIT SCREEN: Several of you let me know about a feature with the ipad that allows you to split your screen and have one app open on one side, and another app open on the other side.
Here's a video that explains how. This would allow you to have a reference photo open on one side, and any art app open on the other. This is a great workaround for the photo reference problem I mention later.
(update) USING LAYERS TO TRACE: One of the apps I've tried (Artrage) has a great tracing feature. A few of you pointed out that ANY app with layers (which is most of them) allows you to trace. Simply insert a photo onto a layer, add a new layer on top of that, trace the image, and then hide or delete the layer with the photo.
Here's a video that explains how to do that in Procreate.
(update) BRUSH PACKS: Different artists sell or give away digital "brushes" they've created and refined for particular apps. For example, you can
go here to get a set created by Tiffanie Mang for Infinite Painter, for free! There are lots of others, although I haven't found a comprehensive list or "store" for them. Unfortunately. I have just kind of bumped into them randomly when I'm looking at various digital artists.
Now on to the apps in particular. (note: touch/click any image to enlarge)