I dont know, the whole 'Drift' thing was a new concept for me, all the games I played you'd have to slow down for curves. :| I've never played Need for Speed so I may be biased in my opinion, but Ridge Racers is so visually stunning and fun to play that I'd stick with Ridge Racers.
Besides, I heard NFS:Rivals has a lot more Japanese text, and isnt as 'import friendly', whereas Ridge Racers has some English (Main Menu : English) and is easier to understand.