Kylie Jenner vs. Demi Rose -- Who'd You Rather? (Tyga's Babes Edition)

It’s a battle of the tigresses.

Tyga couldn't keep up with his 18-year-old ex Kylie Jenner (left) ... but it looks like he has no problem rebounding with 21-year-old British model Demi Rose (right).

Either way he's stimulated.

The question is...