Personally, I love Ibispaint, it's got lots of tools and I know many artists use it, very user friendly and I thhink it's my #1 through all my art apps

Personally I didn't like Kritacwgen I used it, but I do love ibis!

I use procreate for everything - manips, regular art, graphic design projects, etc. I personally love it because it's easy to manuever and learn and has a pretty nice animation feature which is something I love doing XD
But it works great for manips! All the ones I've ever done have been on procreate.

I know many people use ibis for both manips and art but personally I find it fairly hard to learn (although I have premium XD). I like to use procreate for the main work and then sometimes use ibis for different texts and effects, although Procreate allows you to add fonts and has most of the effects ibis does.

I personally have not ever done manips on Medi or Krita, but used to draw on them both years ago. I dislike both honestly because for me, they were quite hard to learn quickly (despite tutorials), and Medi doesn't have a symmetry tool which I find is very important.

I'm aware Procreate isn't free but it's a one time payment of just 10 USD if you decide to look into it. Otherwise Ibis is probably the next best as it has a huge range of tools and quite a lot of tutorials^^

Ibis was really easy for me to learn and I really liked it! I couldn't figure out Gimp, or Krita, but I've heard they are good once you learn them!