rabbit and WCS are the best
ok, with the essential comment out of the way... any server works fine with any bot, its a common winmx protocol, so all servers send out the same things to remain compatible, and clients all send out the same things to the servers, if a certain client were to try and do something differently to the standard way of doing it then it couldn't connect to any rooms, same with servers - clients couldn't connect unless the server supported the winmx protocol
the preferred choice of server for most people is WCS, and the preferred choice of bot is Metis (for some unknown reason
) but you can pick any server and any bot and they will work fine. just remember that if using a server with coloured text you might have to disable the colours for the bot (differerent servers have different commands for that, but its /bot in WCS and i believe also FXServer, others should have some command for it)