G19 for sure if you are only starting out with competition shooting but plan to use the pistol for daily carry.
The G34 will be too long and heavy for your typical CCW. It's really geared towards serious pistol competition.
I use a G19 for IDPA and 3-gun while my roomate uses a G34. He shoots a bit better than me but is also more involved in pistol shooting. I'm more into rifles and shotguns.