Funny, all three of my favourite pokemon come from the 3rd gen. Not that any of the 1st or 2nd gen ones are bad. Or 4th for that matter.
I actually think that all pokemon are fairly well designed. They're all based on some animal, myth or other object or whatever and are quite clever overall. Even the supposed "clones", like Pidgey-Spearow-Hoothoot-Taillow-Starly are based on different birds and IMO, are all worthy of being their own pokemon species.
The only Pokemon that has "made me sick" is Claydol, and only because of it's looks, not it's unoriginality, which it has none. I got used to it, anyway.