I find the feature Digital Playground stuff pretty damned frustrating - pretty but severely lacking in heat - the Island Fever stuff is VERY pretty. They've done some great stuff though in their more gonzo series like "Teen America" - #1 and #5 are sensational! Control is unique and very kinky. Throb has one of the best Krystal Steal scenes of all time. Story of J is quite unique and hot, even though it's very arty.
Overall, I think they're probably the strongest all-around porn company going.
When I think Vivid, I mainly think, "Oh, they're still around?"
Wicked are quite a bit past their prime.
And the gonzo outfits are not well-rounded in their output, though I like a lot of what they are doing.