You can listen to the Glockers all you want, but your best bet is a CZ Sp-01 Shadow.
There are multiple reasons for this gun. Its a 9mm, cheap ammo, as mentioned with the Glock. That is about where the differences stop. The Shadow is a DA / SA semi with a full dust cover and an amazing balance. Comes out of the box with fiber optic sights and is ergonomically sound.
The best part about it is the trigger pull. Its DA pull is about 7lbs, which is perfect for your first shot in IPSC, but after that, the single action pull breaks at around 2lbs. Thats something you wont find in a Glock or XD. They are duty pistols and the trigger will always break the same. With a 3.5lb connector and a polish you might be able to get the Glock down to 3lbs, still short of the Shadow.
Im not knocking the Glock at all, I own one and I love it. But if your thinking of doing any competing, I would go with something a bit more tuned and still in the same price range.
For the price, a Shadow MSRP around $750, the mags arent stupid expensive either should you choose to get active in IPSC.
Just my $.02