I'm going to go way out on a limb here and recommend you get the 10mm, model 20 (fullsize) or model 29 (subcompact). Factory ammo for it isn't really any more expensive and if you reload yourself you can really wake it up with the full power loads. The original 10mm round was a wildcatted .41 magnum that was adopted by the FBI back in the 80s but a lot of their smaller agents and female agents complained about the recoil from the full sized 200+gr bullet so most of the factory ammunition out there is smaller and less powerful in order to duplicate the performance capabilites of the .40.
I'm probably offending the .40 shooters who don't like the full powered 10mm rounds and the 45ACP guys who never seem to think anything less than .450" is big enough, But I'd wanted a 10mm for the longest time and I finally found a good used S&W 1076 for a reasonable price about three months ago. I'm almost positive that Glock is the only arms manufacturer making a 10mm auto at the moment because Colt's Delta Elite, S&W's 1076, and Bren's Ten were all discontinued.
Now I'm definitely a guy who's guilty of liking a caliber just because no one else shoots it (I've got a ton of weapons in weird calibers that no one else shoots) but I'm being perfectly honest when I say that the 1076 is probably my favorite of all the (way too many) pistols I own. The 10mm still puts a smile on my face every time I pull the trigger.
BusaCruise is right on though, the Springfield XD is pretty much the best .40 on the market right now. Great gun, good feel if you're not crazy about the grip angle on Glocks, GREAT price, and a decent holster/mag holder included. (Mine is in .357 Sig, but then again...that's me and my weird calibers again, plus I can always throw a .40 barrel in it and shoot 40 S&W if they start selling barrels separate)