It's about time that I jump into this thread since besides VP, slots are my cup o' tea.
Favs:
MG Slots:
The Thunderstruck template slots (Ladies Nite, etc). I have pounded a few affiliate's accounts back into the stone age with these.
What a Hoot - too bad Spearmaster is no longer an affiliate of Maple Casino. We would be hearing him bitch and moan about what I've done to his affiliate account recently.

Sun Quest - from the old MG days pre-viper. I like it for nostalgia's sake.
RTG
I've done some serious damage recently at iNetBet at the
Aztec's Treasure slots (I like the multiple wild function).
Even though the dude in Mister Money makes me want to punch the smirk off of his face - the bonus games are pretty good.
Same with
Sunken Treasure and
Viking Voyage.
Playtech
I like Chinese Kitchen - fun game.
And some of the newer ones I like as well. (can't recall the names) The Desert one and the Doctor Love something.
Wagerlogic
The only marvel comic ones I play are Blade, The Punisher and the Hulk. mainly because I like the bonus features. I do find these to be tighter than a fishes butthole sometimes
Bejeweled is addictive. I've done well with
Haunted House and
Sirens
Bottom line is that I really like free spin features or unique bonus games.
Slots that I hate
Anything with coins. I can't stand not being able to convert the coins to dollars with a mouse click. They can do this on the slots in Vegas, why not here? I'll be damned if I have to sit here and figure out what each win is worth by converting coins to dollars in my head. :machinegu
Any three real one line slot. Don't waste my time please.
Any slot that makes me want to defenestrate my computer monitor. Harvey's - what a smirky dweeb!