We've owned both the XBox 360 and the PlayStation 3 since their launches. We play both of them regularly. If you're looking into these two systems, how do they compare?
First, remember that for most gamers, it comes down to the games that are available. If you LOVE the Halo series, then really, nothing else matters. You'll want to get the XBox 360 to play Halo on, since it's not on the PS3. Similarly if you are a huge fan of the Final Fantasy series, and adore every game in that series, you will want a PS3. They simply aren't found on the XBox side.
So the very first thing to do is to go to the XBox site and look through the list of all XBox and XBox 360 games. The system is pretty much fully backwards compatible for main titles. Then go to the Sony site and look through the list of all PS1, PS2 and PS3 games. Again, the PS3 is doing a good job of being backwards compatible. Is there one side or the other that has games you adore? If that is the case - and most especially if you have a large library of games for one system or the other, that is the system to go for.
It's like having a bookcase and wanting to fill it with books. If your friends tell you the 100 best mystery books - but you hate mystery books and love horror books - it doesn't matter how great those mystery books are. You simply won't want to read them. The same is true for gaming systems. If one system has 100 superb sports games - and you hate sports games - does it matter? You need to choose the system with the games YOU want to play.
That all being out of the way, let's assume that somehow both systems have the EXACT SAME number of games that appeal to you. So you are on the fence and could go either way. Let's also assume you can only get one system for financial reasons :) So, how do you choose?
Yes, the XBox 360 had quality issues when it first launched. Remember, it was the very first of the 3 systems to come out, and the first to launch always has issues. It comes with the territory. We had our 360 replaced (for free) because of that and the new one has been perfectly fine. The PS3 hasn't given us any problems at all. So if you're buying a new system now, that shouldn't be an issue.
How often we use them for gaming comes down to which games we want to play, which relates directly to the discussion above about "what games do you like to play". For example when Halo 3 came out we were playing a TON of Halo 3 on the XBox 360. However, there are spells when we're playing a Final Fantasy game for weeks on the PS3. Guitar Hero spelled hundreds of hours for the XBox 360. So it's not like we sit down and say "we think the PS3 has slightly better graphics, so let's play that." It is very much that we say "Let's play Guitar Hero!!" and then if it happens to be on the XBox 360, that is what we turn on.
The ONLY reason we choose one system or the other for a non-game-specific reason is playing Blu-Ray DVDs. We have a nice high definition widescreen TV, and Blu-Ray DVDs are so much nicer to watch than standard DVDs. So if we want to watch a movie, we'll turn on the PS3 in order to watch our Blu-Ray version of it. We have the DVD remote control and it works really nicely.
So there you have it. You can read all of my reviews about the graphics specs, audio specs, etc. but when it comes down to it, it's about the games you play. You really don't think much about the different shades of graphic ability when you're in the 8th hour of playing your favorite game. All you think about is how much fun you have playing a game you love.