Dave Foley does the voice of Yes Man?! I should really play with the sound on more
As for favorite characters I'd say
FO1: Maybe the Overseer? You don't see or hear from him much but his motivations and intentions are pretty compelling despite his lack of "screen time".
FO2: I am ashamed to say I haven't beaten it, or even played much of it at all, or even...that I didn't like it much [cower]
FO3: The Elder probably as he was faced with a tough choice that we see echoed in FONV. Continue with the mandate and mission of the Brotherhood, which is move in secure technology and information and move out? At what cost? Stand idly by as the wasteland around them consumes the people and effectively doing nothing to benefit humanity or civilization? Very deep
FONV: Definetly Caesar. His motives and rationale were very excellent writing and certainly put a very interesting, if pragmatic, face on the Legion