1) Paco Rabanne 1 million is pretty popular, but I also like the Hugo Boss Red. A quite expensive one is the Paco Rabanne Invictus (it's very new) but I think it's going to be reasonably popular. Davidoff Cool Water and Hot Water are decent bets.
2) Burberry Weekend is pretty decent (and cheap) for day-to-day, but I don't think it could hold up to a night out. Some people like Aramni Code. Joop jump is decent (and reasonable).
3) Not sure what the difference would be between 2 and 3, but The Body Shop (!!) do a surprisingly decent one called White Musk Sport I think, which always reminds me of a post-exercise smell (in a nice way!) Failing that, any of the Addidas/Nike aftershaves also smell decent. Aramani Code Sport is probably a bit on the higher end price-wise, but would be decent.
If you're just starting off, I'd get something from 1 and something from 2 (or just from 1 if you can't stretch to buying two aftershaves at once, they can be pricey) Get yourself down to Boots or Debenhams and sniff some of the aftershaves to give yourself an idea of what they smell like. It'll probably be cheaper to buy them online though. If you can take a lady-friend (or your mum/granny) with you, it might be easier as well!
Disclaimer: I am 100% certain that I've missed off some very good aftershaves from here, so wait to see what other people say, and then you can collate the results.