Both are great guns, but I sold both my Gen3 & Gen4 G19's and kept my P229 and here's why...
1. The P229 points more naturally. Even when all I shot were the six Glocks I owned, occasionally I would aim high. I don't have that problem with SIG's, Beretta's, and M&P's (except a tiny bit with my Shield once in awhile).
2. The P229 is a three caliber gun if you want it to be, and going between .357 SIG, .40 S&W, and 9mm merely takes swapping barrels & magazines (for the 9mm). All the other parts are shared with the exception of the sights (SIG uses different ones for 9mm/.357 SIG and .40 S&W, but I used XS Standard Dot sights and merely dotting the "i" makes it easier for my eyes). I like it in particular because I am a .357 SIG fan. I have a Bar-Sto 9mm conversion barrel so I can save money (like LEO's used to do shooting .38 Specials out of their .357 Magnums).
3. I like the weight of a P229 which makes .357 SIG softer than a G32 and 9mm even softer than a G19 in my opinion. Yes, it has a much higher bore axis, but that is again mitigated by the weight.
4. I prefer DA/SA guns. Don't get me wrong, striker-fired is fine and three of my subcompact carry guns are of that variety (as it's easier to engineer a small striker-fired pistol with a good trigger in my opinion).
5. I prefer the ergonomics of the P229 even though the G19 is very ergonomic in my opinion. Remember, "ergonomics" is about efficiency (it is not a synonym for "comfort" despite how it's normally used in a sentence in the gun world). In other words, the Glock grip angle forces the shooter to cant and lock his wrist which helps with recoil control (which is efficient for that purpose, but I prefer a more naturally pointing pistol).
6. I am more accurate with the P229 (the SA trigger pull with the SRT is a much better trigger).
That's it. I am sure I could have teased this out to ten reasons, but honestly this was all I really cared about. The G19 is an excellent pistol so you can't go terribly wrong with either one.
That said, although Both are technically compact pistols, the SIG P229 is 5.4 inches tall. It's not a deal breaker but while my P229 replaced one of my G19's, my Beretta PX4 Storm Compact replaced the other and it is a closer competitor in my opinion coming in at 5.0 inches in height. Better yet, it is essentially a Glock 26-size slide on top of a G19-size frame with Beretta 92-like controls and trigger system. I love that pistol. Both are great and I wouldn't want to choose, but I do choose to carry my PX4 Storm Compact far more often.
Ernest Langdon has really helped up Beretta's game in this department (especially with the "Optimized Performance Trigger Bar" he just came out with which allegedly gives it an SRT-like reset). Even without it the PX4 Storm Compact is one of the best "compact" pistols on the market, and with the shortened reset, it may edge everything else out in my opinion. I haven't received mine yet, but that was really the main thing that distinguished my P229 Enhanced Elite over my Beretta (trigger wise).
I'm not saying the Beretta PX4 Storm Compact is the right pistol for everyone, but it's certainly worth looking at closely, especially if you can get a good deal on an Ernest Langdon model.