Partner Pokemon: Neeee-dooooh-reeeee-naaaaah~
Why'd I join: Because my memory is spotty and the only Pokemon I can remember most of the time come from the first generation. Most of my favorites are from there, too, but that's probably a side effect of the first reason.
Current Topic: Er, I don't really think any of them are extra special. In a way, that's what either makes them great, or what makes them bland depending on the person's viewpoint. I think from an illustrator's point of view who loves detail, other generations have been better. From an animator and character designer's PoV, though? Designs from later generations are atrocious and unnecessary. You're going to get way way WAY more pencil milage out of the first generation, trust me.
There's a reason the designs became more streamlined in the first generation in the first place. Compare Sugimori's Red/Green art to the way the Pokemon look now. Check out how much asymmetry is in the old designs. Cool, right? Now try drawing those little details in an animation over and over and over and over and over again. And that's just for a 5 second bit of footage. Do this again for months, and you've finally got an episode. Oh wait, you're not finished yet, now do the other 51 episodes! You can see why they made stuff easier over time.
I symphathize with animators, so I like the first 151 because they're simplistic. Though I'd agree Gyarados probably has one of the more complex designs.