Probably down to personal choice really however I've had my PS3 for a month now and have played a few games so thought I'd share my experience to date.
- Ridge Racer 7 - fantastic and addictive game; would highly recommend
- Ratchet & Clank:Tools of Destruction - enjoyable platform game and very funny; would highly recommend (demo download available from PS store)
- Gran Turismo 5 Prologue - more of a challenge than RR7, more 'realistic' but I didn't find it as much fun as RR7
- Motorstorm - very enjoyable off-road driving game, a real riot; highly recommended (demo download available from PS store)
- Guitar Hero III - I never really got into this however my 16 year old son loves it and he is a very accomplished electric guitar player (Slash standard solo's); I'm 45 by the way, you're never too old for video gaming!
- Unchartered: Drake's Fortune - I've only just started that game but am really enjoying it so far; excellent gameplay and graphics, would recommend(demo download available from PS store) .
I've also just ordered Lego Star Wars:The Complete Saga and Timeshift; the latter I tried on demo and really liked. Would highly recommend using the free game demo download facility from the playstation store; I used that for most of the games before I bought although not all games have demos. I normally use this site to find the best prices
http://www.find-dvd.co.uk/videoGames.aspx.
Hope this helps. I love the PS3; best system I've ever had.