I know this is blasphemy but I've never been a fan of George Perez's work.
There's absolutely nothing wrong with it technically. It's usually very well done and very technically detailed and no doubt the man is talented. I just don't like the style of it and I'm not entirely sure why. I think it's something to do with the way it's usually inked or maybe I'm just not a fan of the way it still leans towards the Bronze Age look or maybe I just don't like the way he draws faces.
Alan Davis.
Not because his art is ugly, but because I can't stand everyone having the two middle fingers touching thing in EVERY. DAMN. PANEL.
George Perez and Alan Davis are the hottest takes I've seen yet. Both are top notch to me, and have been for decades. Perez on NTT and Davis on Excalibur are iconic to me. But I appreciate that both of these weren't just hot takes but did provide some explanation. However if someone brings up the likes of Art Adams, Chris Sprouse, etc. then we have a fight on our hands.
Can't believe people think Romita Jr. used to be bad.
I actually loved the blocky style that Romita Jr. had when he did Spider-man, Daredevil, even his second stint with the X-men.
Some artists, it depends on the project:
Ramos is very cartoony and loose, and I like him better on characters like Impulse or Spider-man. I think he's gotten better with his layouts, though.
Bagley is another one where I don't love his art, but I think he did a great job on Spider-man, but his stint on Justice League was... mediocre. I'm not sure if that's because I associate him so much with Spider-man and Marvel or what.
Bachalo has a great style but it's so chaotic. I couldn't tell what was going on at all in his Image series, and even his X-men run was so chaotic. I feel like he's regressed since his Gen X days.
And lastly two artists I think improved a ton:
Someone mentioned Jae Lee but I remember when he was a hot artist on Namor and I just couldn't make heads or tails of a lot of his panelwork. By the time he got to Inhumans he seemed a lot more refined.
Travis Charest was like the cloniest of Jim Lee clones when he started out, but (ironically) by the time he took over WildCATs I actually preferred his work over Jim's.