Its down to choice but general views on both are,

Exclusives - debatable do you want Halo/Gears of War or Uncharted/God of War/Demon Souls this is down to you but most of the recent exclusive high rated games seem to be on PS3.

Build quality - PS3 is by far the best built,most 360 users you speak to have had at least one issue.

Online - Xbox live is generally considered much better, PS3 is free though.

Blu ray - PS3 only and yes its very good, also you can update the HD and fill it with bluray rips ftw.

3D havnt seen this mentioned PS3 only and its coming very soon films and games you do however need a 3d tv.

motion 360s natal looks very good on previews,not reviewed yet though, PS's move not gone down brilliantly so far.

Bear in mind the 360 is due to be revamped also soon.