If possible try and shoot both guns, and take the one that "feels" the best. As for 9mm vs. .40S&W, you'll hear a lot of different opinions. Ideally I'd like to have a semi-automatic that shoots .45ACP, holds 20+ rounds, have the size of a small .38 snubbie, and weighs in at 15 ounces loaded.
A semi-automatic like that does not exist... so you compromise. As you chip off a bit here, and a bit there, you end up with something like the Sigma, or the SR9. ....or like in my case the SIG P250 in 9mm.