I probably wouldnt be able to decide and therefore, would just go buy a 12g. shotgun instead.
But, seriously, some contend that a revolver can endure much more than a semi-auto. I believe, in certain cases, it can. It is not an infallible weapon, however. Of course, neither is the semi-auto. But, many current semi-autos have certainly upped the ante' when it comes to overall reliablility.
Basically, if I were to want a weapon which required little to no maintenance, was very durable, would be sitting around for extended periods of time and was capable of handling extremely effective HD ammo, it would probably be a stainless steel revolver (specifically a .357 Magnum). If I wanted a weapon which, while requiring a bit more maintenance, still had a good reliability track record + the advantage of mag capacity, was more "mod" friendly, possibly offered quicker reloads, was "easier" to shoot when using powerful HD type ammo, etc..it would be a semi-auto (depending on caliber).
Needless to say, it kinda hard to pick just one as they both address certain issues in very effective ways. Overall, given the quality of todays semi-automatics, Id probably go that way. It seems like the old revolver/semi-auto reliability argument has become less and less of an issue given todays selection of weapons (semi-autos), IMHO. In terms of caliber, I would probably opt for .45 ACP...if I could only choose one. And this choice would NOT involve a Glock. Given your proposed choices however, Im just not sure. But, if one were to "twist my arm", Id probably go with the Glock. Not because Im a huge fan, but because I do realize that the 9mm variant of Glocks are among the finest guns you can buy in that particular caliber (the Sig P226 notwithstanding). And while the 9mm certainly isnt as effective as say, 125g JHP .357 Magnum loads, it can still do whats necessary, particularly when using a +P or +P+ variant. This is in addition to, I believe, allowing you to maintain greater control which should result in greater accuracy/efficiency.
But, with all of this said, its basically up to what "feels" best to you. For instance, a lot of folks just dont like the way Glocks "fit". So what if its a great gun. If it doesnt work well for you, it would be a bad choice in this case. Same goes for the .357 revolver. If you find that, when shooting full-house .357 Magnum HD loads for instance, you cant hit where you aim or that you arent crazy about the "buck and roar" of such loads, this would not be good for you either. Just be aware of the positives/negatives of both guns, both including and in separation of caliber. Then, go out and shoot them. At that point, it will be all up to you.....regardless of anybodys advice.