"What I'm looking for is that penetration and expansion."
First of all, if you increase expansion you REDUCE penetration. High velocity is necessary for expansion. But, most handgun rounds, especially out of a short barrel will fail to expand when shot at bad guys (of course, penetration is usually excellent as a result). The reason is not just because of the low velocity, but because the hollow points fill up with clothing, drywall, etc. which makes the bullet behave as a solid (unless you are shooting naked bad guys). I would opt for the 38 +p round as it is easier to control (thereby resulting in better hits), less muzzle blast and faster and more positive unloading and reloading with the shorter case. It is still authoritative enough.