Hm... Multiple legs seems more likely I suppose.

Just call me the centaurpede. :P

Taur-train? :3
http://www.furaffinity.net/view/15051616/

I think the naga transformation. Even a 'taur would provide some frame of reference because of its limbs. Having a complete lack of lower limbs would require some considerable adjustment.

I'm going to have to agree with flafty above there. That and no frame of reference aside from trying to figure out what snakes do.

Better be ready to trip a LOT. Wear a protective mask. :X

Plus, how dirty is your naga belly going to get?

That water bill for bathing is certainly not gonna be pretty. D:

Naga, definitely. As different a form of locomotion as four legs would be, no legs at all and having to rely on full-body movement to get around would be very unusual indeed.

Add to that the very different reptilian instincts, and it's a very different mental impact.

Add onto that the specific traits of different snakes. Stuff like they tongue being used to smell (or if the nose is still largely the same, the tongue would be an extra way to smell. Or stuff like heat-pits, which would give the TF'd individual a sort of heat-vision.

A taur is also largely bare to the world, barring some very carefully made clothing, which they'd probably require help from someone else to put on. A naga, on the other hand, would probably be stuck with only wearing clothes on their upper-body. The rest of their length would, unless clothing is magically held in place, be completely bare. For an individual used to wearing clothes all their life, it'd take a lot of adjusting.

And just so it's said: Depending on where the genitals ended up, it could take a lot of getting used to, to say the least.

Probably naga since I'm already a taur! :P

Naga is definitely the more difficult transformation to adjust to; ssJ3's break down of it is really good. And I've been both taur and naga and like them both!

Dominus tecum

While both are cool, I'm gunna say naga if only because instead of having to worry about walking with lots of legs, you gotta deal with walking with no legs. Also, nagas can't really move well while wearing a nice pair of pants.

Nagas all the way! Although I love taurs too, I agree with most of the people above on the fact that dealing with no legs would be a completely new experience as compared to having a few more. As with legs, you'd only need to coordinate a few more limbs, but as a naga you'd need to coordinate all the muscles of your serpentine lower body! Definitely much harder to adjust to in my opinion.

The more "Alien"? Transform into a Xenomorph.