There is one overwhelming defect that kills illustrator, at least for some of us. It lacks the essential selection mode that Inkscape, Corel Draw, Sketch, and others have: only selecting objects that are totally enclosed by the marquee.
Illustrator insists on selecting everything the marquee TOUCHES. The straight-up stupidity of this limitation becomes obvious as soon as you... well, do almost ANY drawing. Did you do a wireframe of a UI, but want to shift a group of labels? Have fun selecting each one separately instead of just drawing a box around them.
The problem may not sound like a big deal if you don't work with this kind of app, but it is. It's a deal-breaker.
Why can’t I just draw a line from one part of the path to another and have it recognize that.
There’s no trim feature, you have to mess around with whatever the hell the join function is.
I’m coming from fusion 360 where everything is an intuitive dream to work with. Illustrator is straight trash.
There's also Sketch, which offers a more limited toolset than some and seems to target UI design. Not bad. Some unintuitive UI and some bugs here and there that aren't getting fixed, but you can get stuff done and it's supported by quite a few design-collaboration platforms online. There doesn't seem to be any official user forum for Sketch, though, which is annoying. Someone can correct me if I'm wrong on that.
Corel Draw, which is Windows-only, has always been better than Illustrator. It's pretty good.