PPK's look nifty and are just plain classic, but I've heard very mixed reports new ppp/s. I went for a p99 compact. But the ppk and p99 in .40 seem to be worlds apart aside from rumored reliability anyway.
My new PPK/S by Smithy has 500 rounds of various rounds, mostly WWB and Federal Hydrashok with ZERO malfunctions. It think the initial batch was possibly problematic, but mine has been PERFECT. I shoot just as well, if not better with it, than my P99. And it's darn thin, easy to conceal.
However, remember, for every gun that has a problem there are the vast majority that don't.
I'd go with the P99 compact to gain the advantage of a larger caliber (9 or 40). The PPK is a classic, after you get a P99, maybe you could get a PPK just to say that you have one. Either will serve well, I think.