I just sold an XD9SC and a XD40 Service to buy a Sig P229 SAS Gen 2. The only thing I am regretting about my purchase is not doing it sooner, so I guess you can figure out which one I vote for. The extra capacity of the mag is not important to me; if I can't do the job with 14, then the extra six is probably not going to help either. FYI, as I understand it, Sig is now shipping all new guns with only one mag, so depedning on when your gun was made and shipped, you may be buying one more mag than you planned on.
Which P229 are you looking at?