Since you're familiar with Glock, you might try the Glock 21, 30, or 36 - all .45 ACP's. Why relearn a different set of controls, "grip feel" and sight picture, if you can get a reliable weapon in a more effective caliber? An S&W M&P in .45 ACP might also be a good choice, but the Glock will give you access to TREMENDOUSLY more holsters and accessories than other brands, both new and used. Personally, I love my Taurus 24/7 Pro in .45 ACP, but they're not for everybody.