1. Spy (who did see that one coming?)
2. Solly (only with a good medic, else push down at least 3 places)
3. Medic
4. Pyro (pretty much only to defend sentries from spies and übers. Otherwise I feel like a spy with less damage, no disguise, no cloak and less health

)
5. Sniper (mainly huntsman, the rifle for people who can't aim. JARATE!)
6. Heavy (not bad, but has many, many counters (each class seems to define itself on how to kill heavies) and is very hard if you don't have a good medic on your ass all the time)
7. Scout (looses his appeal as soon as enough people are on the server, plus scout vs scout duels feel very random)
8. Demo (laying sticky traps is boring, pushing towards the enemy is very hard)
9. Engi (build 5 minutes, don't do anything the rest of the match or get it destroyed in a second by über or a spy.)