so much for easing into the addiction.
welcome to the club.
between 308 and 243, I would go with the 243 based on the following reasoning.

I have a 15" factory 25-05 that I am shooting 100gn hand loads out of. haven't checked velocities yet, but they were respectable out of my rifle. It's fun to shoot with mild muzzle jump, I would say I could shoot all day but i haven't had it that long or put that many rounds down range. I have a 308 savage striker that has a much sharper recoil and a good bit of wrist twist that is a lot heavier that I don't really enjoy shooting that much so i haven't taken it out to hunt with yet.