I have to say i dont really like either that much aesthetically but I would get a lotus if it were given to me and sell it for an audi and keep the rest lol.
I really love Audi's and I can imagine how fast and fun the TT must be, but I really can't imagine myself in a Lotus.
Actually a lot of people in CA have Lotus' and they look really funny on the road. They don't even look that cool... so I'd have to go with the TT in a 6 speed!