I always liked Gwangi. It had that different twist to it - cowboys versus dinosaurs - and the animation wasn't too bad.
As for One Million Years B.C., other than Raquel Welch's obvious charms, the fight between Tumak and the allosaur is a highlight. I always remember saying to myself, after the beast is impaled on the spear and is lying there, dying, 'Hey, that thing's breathing! An excellent bit of animation from the master, Ray Harryhausen.