I've got a number of LD players, all Pioneer though: CLD-A100 (LaserActive), LD-717, CLD-D504, and another dual playone. I'm guessing the CLD-D504 is probably the best since it is the latest released.
I've heard a lot of folks say that the s-video on a LD player can actually be inferior to the composite in many cases and is only as good as the comb filter that's being used on the player.
Please correct if I'm wrong, but if LD is natively stored as composite, I would think that would be the most original source to work from. Anything you're getting from S-video would already have gone through the comb filter (which has quality varying by player) from the source composite. I'm not sure if you'd be relying on the capture device to filter everything or I'd then need some extra hardware in between the LD composite source and the capture card to get a better result though.