XLoWRyDaX,
Here are some thoughts on gun ownership - coming from personal experience, I might add.
If I were to own one handgun, and (realistically speaking) if cost was a concern, I'd go with a Glock 19, in 9mm, hands down.
Why? Glock 19's are probably the most durable pistols on the planet, are capable of digesting upwards of 100,000 rounds of ammunition in their service life, are reasonably accurate, and
are compact enough for concealment, but large enough to be a primary arm.
Pre-ban capacity was 15 rounds, and "new" pre ban mags (at least factory) are astronomical in price...however, ProMag's copy works very well, and CDNN is selling them for a very reasonable $25 or so right now.
Even without the extra 5 rounds that the hi-cap mag provides, the Glock 19 has one thing going for it that the .357 SIG doesn't - price of ammo. Surplus military ammo (from around the world) can be cycled through your Glock...allowing you (time permitting) to shoot (most likely) 2 to3 times as much as you'd be able to afford with the .357 SIG.
Knockdown power? Well, it seems that there's a never-ending argument on that issue - used to be 9mm versus .45, then it was 9mm versus the "new" .40, and now the super 9mm, the .357 SIG. Even so, does it really matter any more, with most trainers in agreement that one should "keep shooting until the target drops" anyway?
If you're a new shooter (no offense if you're not), you won't find a better carry gun. The Glock 9mm is truly a jack of all trades firearm, and I give it my highest recommendation. Used ones are being sold for anywhere from $350 to 400 from most dealers, and from advertisers in Shotgun News.