PS3 in general I have found more reliable and their customer service great. I've had one of mine break after 2 or 3 years of owning it. Didn't have insurance or anything and they replaced it in a week with a new one for free!
It also has loads built in such as bluetooth, blue ray reader etc. The blue ray reader means the disks have the ability to have 50gb of info on each one. Xbox still uses DVDs for games and so has a max of about 9gb.
When they came out, there was a big debate over HD DVDs vs. Blueray and Sony won that one, and as such most films are coming out mainly on Blueray and they're the main ones you see in shops.
Gameswise they each have some exclusives that are good. Banjo Kazooie for example on the Xbox, and Uncharted 2 on PS3 I believe is an exclusive too.
Having played on both, I must agree that the xbox live service is quicker at finding games (not actually in them, they're the same), but then the extra speed is not something I'd personally pay for as I don't have a regular income and don't want a bill. Gaming difficulty online I've found the same on each.
Physically I have found the PS3 console feels better built and alot more solid. Controllerwise I do prefer the xbox one I think though.
They've each got some good points and there'll always be debates between which one to go for but I personally find PS3 the premium console. I think the price of xbox's is great though, but then they're less well equipped.
Also I don't know what's available for Xbox, but PS3 runs laptop hardrives so don't worry about how many gb it has when looking for one, as it's £50 for a 300gb hardrive and it's very easy to replace.