Schwarzenegger vs. Stallone vs. Van Damme vs. Seagal

For me it's Stallone for all three topics you've mentioned. Although if there was a 4th category for which would win in a pie eating contest I would have to vote for Seagal, I am not sure why though, he just seems like the type of person who would win since he is circumferentially challenged.

I would say Arnold for all three unless it's a Rocky movie.

As an Actor: Stallone, not because he’s a good actor, but because he’s the only classically trained actor

As an action star - I grew up watching Van Damme and the Terminator films were a big part of my childhood. I’d have to say Schwarzenegger hands down, no one really captured that role better than him. Having said that, I enjoy watching fight choreography more and Van Damme and Segal had some great fight sequences.

Better Movies: This one isn’t really fair considering Cameron directed the Terminator films

Definitely Schwarzenegger