The PS3 is better value for your money, it's a Blu-Ray player and a music center. It has optical out built in so you don't have to rely on your TV including optical out or the cable you're using supporting it, so there's simply more flexibility for your sound system, although conversely with the lack of a VGA HD cable slightly less flexibility for your display - although presumably you'll want something of at least 32"-40" so either way you're likely looking at an HDTV.
The PS3 will last longer - with a 360 you need to buy yourself an extended warranty or service plan, and those go no more than 3 years, so you're out of luck beyond that. A PS3 will easily last you 3 years without trouble, and 8-10 years isn't out of the question.
The PS3 doesn't nickel and dime you - no need to buy rechargable batteries or the play and charge kit, no need to pay for Xbox Live Gold for online play, no need to buy the stupid Microsoft Points that never add up perfectly for what you want to buy. Online play is free, everything you need except for an optical cable and HD cable is included, and anything you buy off the PlayStation store can be bought in proper $ amounts.
The PS3 isn't region locked - some games on the 360 are region free, but if there's a fighting game only available in Japan, you can import it without concern that it won't work. That's not the case with the 360.
The PS3 has more connectivity options, since you have BlueTooth as the connection method you're not going to be stuck with an annoying dongle for 3rd party controllers as much as with the 360, keeping your precious USB ports free. You can use almost any USB peripheral as well, like the Sega Saturn USB control pad that's rated very highly for fighting games, there's the wireless SFIV pads by MadCatz, while the 360 gets wired versions, as well as options between wired and wireless arcade sticks. Particularly with fighting games you just have more options to get exactly what you want to play the games the way you want if you're buying a PS3. Also worth noting is there are far fewer options in general for 360 controllers, as almost all the 3rd party ones are clones of the 360 controller. I've had to quit playing my 360 for now and go back to PS2 and GameCube because of the controller, and waiting for the one option that actually has a difference to come back in stock so I can buy it. I know plenty of people have no complaints about the 360 controller, but if you dislike it, as plenty of people do (and who therefore don't own a 360) then you're quite screwed. With the PS3 at least there are a number of companies making controllers similar to or exactly like the 360 controller, so if you dislike the DualShock you can always just buy something else instead.
The Xbox 360 only has two advantages over the PS3, one is the aforementioned VGA HD cable, which lets you use a monitor up to 1600x1200 resolution, which is pretty handy for keeping prices down if you already have one, and is good up to around 24". The other is older games - among the ones that are out already, before 2008 the 360 has most of the good games, and those games are really cheap now. I've found far more games at under $10 for the 360 than for the PS3. $5-$15 is actually a reasonable range to find a bunch of 360 games, whereas you're usually looking at more like $15-$25 for PS3 games (although there are a few $10 PS3 games as well). I'm certainly making the most of those advantages right now, but what it comes down to is the 360 is only a better value than the PS3 if you literally can't afford the PS3 and HDTV - the moment you do have money to pay for stuff it's incredibly tempting to just buy the extras for the 360 that really cause the costs to add up.
If you have an even split between friends playing PS3 and 360 now, get the PS3, you won't have to pay to play with them, and in the long run your 360 playing friends will switch over. Everyone has a break point, be it 1, 2, 3, 4, 5 or 6 times that their 360 breaks and they have to send it in for repairs that eventually they just give up and switch to PS3. I've bought a large number of 360 games and peripherals from people like this at a very low price. That is of course an advantage, so much cheap stuff from people tired of the main system breaking, while everything else is reliable, but of course the harsh reality that goes with that is eventually you'll be doing the same.