The three classes most suited for killing Snipers are:
- Snipers. Some maps in particular are very Sniper-battle friendly at the beginning. Most payload maps are a good example (see: pl_goldrush stage 1, pl_badwater, pl_upward). Pretty much all maps are sniper battle friendly in the middle.
- Spies. Even with a Razorback, a Spy can just shoot you 3 times (twice with the Ambassador, assuming the first shot is a headshot) to kill you.
- You wouldn't think Scouts would be, but it's easier for them to get past Snipers due to their speed.