I would try the $10. If you see that you are not feeling confifent enough to play them after one or two then drop back to the $5 ones.
At least my impression of the $10 as compared to the $5 ones in PokerStars - Ther $10 ones are a bit tougher, you get pretty much the same level of bad players, but the good players are better at the $10 then the $5