For a 9mm, I like the Beretta more than anything, but it will be a bit on the huge side for carry. If you can manage to hide it well, go for it. If not, the 228 is the answer.
Beretta pros:
-180º ejection port. Ensures the round will eject and not stovepipe, etc.
-reasonable 15-round mag prices and plenty of mags out there
-locking block locks the barrel in exactly the same place for each round with no play or movement of the barrel
-extremely wide ejection port. This gun will feed anything!
-looks great
-great trigger in both DA and SA
-action is as smooth as glass
-barrel is .5" longer than most other semi-autos giving higher velocities of different rounds (good for JHPs)
-can handle +P, +P+, and subgun ammo (according to the manual)
-very accurate
Beretta cons:
-front sight is not removable, unless you get a Brigadier model (dovetailed on Brigadiers).
-gun is big. Not a prime candidate for CCW
-safety is slide-mounted. Not an issue if you don't use it.
-DA pull is heavier than the SIG, but smooth
-locking block is the weakest part. Although you may read how they break every 2 seconds, most of that is hype. Having said that, they can break and will probably be the first part to go. Replacements are very cheap (price, not quality) and easy to install. I have never seen any proof of a single locking block failure to this day, only internet stories.
SIG pros:
-15-round mags are very easy to find, even more so than the Beretta, in my experience
-very accurate
-very easy to clean
-feeds anything
-looks great
-grip is thinner than the Beretta's
-slightly smaller than the Beretta
-trigger is lighter than the Beretta in DA mode
-sights are dovetailed
SIG cons:
-roll pin in slide can work free, but usually doesn't. If it does, a new one must be ordered from SIG. Not an issue with the new, stainless slides
-finish blows big time
-light surface rust can form on some parts, if exposed to a moist environment and/or sweat
-new SS slide models are very top heavy
Feel free to add to or dispute my pros/cons.