ACMS,
thats weird...when I was on the tristar as a FO, I told all the captains that the tristar fleet was the best...when I went to the bus, I said the bus was the best fleet. Now as a captain all my FOs tell me the bus is the best fleet. Hmmm...they also laugh at all my jokes!!!!???????
Gravox, there are good and bad points about every fleet. 777 seems to be the best aircraft...400 gives you the best lifestyle...airbus gives you the most varied flying(except your last year as an SO when you will do 3-4 oz trips a month on the 330!).
Join, pass the conversion, get online and then work out what you want when you upgrade. Truth be told you might not have too much say what aircraft you go on...I think the training system is close to melting down from overheating. For the next 2-3 years most SOs will upgrade to the 777. After that, who knows. Basings are a good way to get on a type you want...as long as you are prepared to be based where the aircraft goes.
enjoy!