I'm thinking of buying a Castlevania game to play on the bus, and was wondering which one I should get.

Dawn of Sorrow is the best. The Portrait of Ruin played like it was a step backward and the 3rd one was a little too weird for me.

I would have to go with Dawn of Sorrow for best Castlevania game on DS.

I've not played Order of Ecclesia yet, but out of the other two I'd also go with Dawn of Sorrow. I still enjoyed Portrait of Ruin, but the whole two character thing may have been too fiddly for its own good; the twin loadout system in DoS just seems like a much more elegant mechanic.

Dawn of Sorrow is both the best and the most 'Metroid-ey' of the three. Order of Ecclesia's very good too, but I personally found it a bit too linear. It was almost like a throwback to the old Castlevania games because it's basically set out as a series of fairly straighforward 'levels', each with wildly different backdrops. Portrait of Ruin isn't bad either, but I'd definitely play the other two first.

I enjoyed Order of Ecclesia the most. I certainly recommend it. Dawn of Sorrow is solid as well.