well it redepends on what youre after sound-wise. there are a TON of drivers that could fit most applications. biggest difference between mid drivers is the surround come material. The motor is a duh, but yeah. You can ger something from scanspeak, Daynon reference, silver flute for good accurate sound reproduction, and itll get fairly loud. but if you want it to get actually loud, youll want to get some PA styled drivers and power the ever living **** out of them while maintaining proper xover points to not kill them. Same goes for tweeters. Some will swear by hybrid audio all the way and piss on most other stuff. Dayton also makes good tweeters. I have a pair of massive audio ct2 tweets and theyre boss.
whats your endgame and budget