It wasn't my first love but today, I get by far the best ch3 sound with Extreme + 90W Pentode (EL-34s). The IIc+ mode is just too thin and bright for me (totally unlike my actual IIc+ in that regard), the IV mode too soft/mushy. Once I successfully dialed in my dream sound, channel 3 on my V has never left Extreme mode. Big, ballsy, aggressive, in-your-face sound that can grind boulders to dust.
As for the other two channels, I don't have clear favorites - I just pick the most appropriate modes for the songs we play, typically Clean/Fat for clean sounds, Edge (or, very rarely, Tweed) for oldschool rock, Crunch/Mark I for a bigger hard rock sound.