Well, you want a lot. I carry a 10 mm every day and have for 10 years or so. I have shot numerous IPSC matches with the 10mm. For me, the 10mm has adequate power for serious social work. Is there a possibility of a pass through shot ("over penetration")? Of course. The idea is to be able to penetrate to the vitals from ANY angle. A 9mm can pass through. A .40 can pass through. A .45 can pass through. My 10 mm has 50% more energy than a .45 ACP 230 gr Gold Dot and about 40% more energy than a .40 S&W 180 gr Gold Dot. If I MUST shoot someone, I want them to stay shot. If they are wearing body armor, I want to break things and knock the wind out of them so I can follow up as needed.
The 10mm in the hotter loadings is not for the faint of heart. You are shooting a Magnum class handgun. With the compensated Glock barrel/slide combo, the recoil is negligable. Follow up shots are quick, easy and accurate. In my S&W 1006 it was harsh w/o a proper recoil management system like the Sprinco recoil reducer.
The 10mm is the most versitile auto loading pistol round currently on the market. From super high speed 135 gr bullets to Subsonic 180's to hot 175's and 180's to hard hitting hard cast 200 gr flat points, it will fill nearly any niche short of deep cover.