Even seeing Nemmy on that list makes me sad. Yes it's day will come but I think the park love it as much as us. When it's day does come I think they should leave the track there as a permanent monument. It's a work of art in itself and the area should be opened up so you can walk around the whole thing. I'm just in denial about Nemesis ever getting old
My choice would be Air. Oblivion is a great concept and is the centrepiece of X Sector.
I've never been a fan of Air and the Galactica thing was cool but the ride is too short to really justify the extra loading/unloading times it creates. I was also weirded out by the fact I couldn't see my hands! I doubt many people would even notice if Air was gone tomorrow. It needs replacing with something more fitting of Forbidden Valley.
I rode smiler for the first time today. I was on the fence about it before but when I saw it in the flesh I was impressed. I did come off with a big smile on my face, helped somewhat but the unusually long ride time. I really like it. Most of the ride is spent upside down but it never felt like inversions for the sake of inversions, unlike Colossus.