Like some have said money no object get both, but getting two new consoles at once could be strange and a bit overwhelming. This is how i see it, ill try not to make un needed negative comments on either side to keep this thread friendly. It will have more to say about the PS3 as im an owner of one but have played and used a 360 many times.
The 360 has more games in each genre as its been out a year longer, Xbox live with its large features list of extras cost £40 a year, some people like chasing gamer scores and acheivements which is all a part of the Xbox experience IMO. It has some of the biggest selling games this gen and some good (potentially) console exclusive games coming out this year. XBLA has more games than PSN and has some very good Japanese side scrolling shooters currently. It is an excellent games machine and a pretty good media centre, its a great console and the new ones are more reliable than previous models.
The PS3 on the other hand has yet to come of age, at the end of last year games such as Ratchet and Clank and Uncharted showed us the PS3 could match and I and many proffesional game reviews say eclispe grahically anything currently on the 360. The PSN network is free, but is not as feature packed as Live although things such as in game messaging are being introduced in many new games. All Sony 1st party MP games ie Resistance, Warhawk have dedicated servers so gaming is Lag free much of the time on these games, they also support 32 (warhawk) and 40 (RFOM) player games.
Early ports of 360 games were poor in relation, but still in most cases perfectly playable although perhaps missing some of the polish of the 360 games and in some case poorer framerates. EA games have suffered greatly from this, but now according to EA they have got over most of the issues, 360 EA prob will have the slight edge this year but next year will be equal.
This year Sony launches home ( see thread on here) which is kind of 3D myspace, secondlife, youtube, gamelauncher (cant think of any other way to desrcibe it) this is supposed to bring all that live offers and more for free in an interactive world. With BD being the only HD disk format, and microft saying they are not interested in a BD add on for the 360 the PS3 will be one of the cheapest BD players and one of the best.
The PS3 and 360 have some great beat em ups here and coming, there's Soul Calibur 4 coming june i think, the PS3 has Darth Vader as a special character and the 360 has Yoda, Tekken 6 should be out this year (PS3 exclusive) and possible king of fighters 12 (also supposed to be a PS3 exclusive) as well as the others mentioned. Dead or Alive 5 has not been confirmed as an exclusive for the 360 and in an interview with team ninja about the PS3 and ninja Gaiden Sigma they hinted that it wouldnt be. Driving games this year the PS3 has ferrari challenge game out next month, 16 player online, damage, etc and GT5 prolougue out at the end of march, its way more than a demo more like Gran Turismo lite IMO. Again look on the thread on this forum
Im not going to recommend which one you should get as its your money and your opinion, but look at the games out and coming this year, look at the features each has and which you will use now and in the future. I wouldnt get a console based just on past games and games out this year, it should be an investment to last 5 years, so which console do you think will have the best future regarding technology, support from first party, and other game developers thats also got to be considered.