i can only say nice things about crucial. because that's the only RAM i've ever used. and nanya i've never even heard of. so i don't know if they're still around, or whether to say good things about them. i'm frankly amazed that these ram cards are still good. i ran memtest and amazingly, they check out. so kudos to them.
I've used G.Skill, Crucial, OCZ, Kingston and I really don't have a favorite brand. I do like my DDR600 G. Skill memory I have. It'll run at 2,2,2,5 timmings at 400MHz or 2.5,4,3,5 at 600MHz. To bad I only have 1GB of the memory. I don't have any experience with DDR2 yet. I'm thinking that I won't change motherboards until DDR3 becomes mainstream, and by mainstream I mean until DDR3 costs as much as DDR2 does now.