Josh Keaton as Peter Parker/Spider-Man. He is just perfect in the role. He can show versitility between a younger and older Spidey, and shows differences between his Peter and Spidey. He captures the character's angst and wit well in a subtle, but remarkable, manner.
Steven Blum as Wolverine. I was introduced to his performance since the X-Men: Legends games, and has been a perfect fit ever since, even though I'll admit I never cared for the character much.
Eric Loomis as Tony Stark/Iron Man. Yeah, I never played the movie tie-in games where he first debuted, but I warmed up to his voice after watching enough episodes of Earth's Mightiest Heroes.
Brian Bloom as Steve Rogers/Captain America. Unlike Loomis, Bloom impressed me from the get-go as Steve. Captures the character's air of leadership and courageousness.
Steve Blum as the Green Goblin. This pretty much showed me how talented Blum is. Very distinct from his other voices, while being recongizable at the same time. He gave his Goblin plenty of insanity and viciousness, while being snarky and funny at times as well. Also liked how his Goblin had a pitch that could fit either Norman or Harry's voices, adding to the mystery bit.
Alan Rachins as Norman Osborn. Pretty hard to believe that the same voice actor who voiced Clock King would do Osborn, but Rachins pulled off the greedy, sociopathic businessman pretty well.
Tom Kane as Ultron. Though I kinda wanted to have Wally Wingert as the evil Ultron as well, to add more eeriness to him, I ended up really liking Kane. Ultron was, by far, my favorite villain in season one of EMH, and I anticipate his inevitable return in the second season.
I have A LOT more coming, including more X-Men, Avengers, Fantastic Four, and Spidey characters!
"Aaah...your screams are like music to my ears" - MODOK