I played both equally i finished Jak and Dexter the first 3 of them but only really enjoyed the first. It was a pure platformer game! But then the guns and car stealing came and its like GTA for kids!
Ratchet and Clank i finished the first 3 and really enjoyed them all espicially the multiplayer on the 3rd one! So Ratchet and Clank get my vote it was awesome all of them!