Which older Canon Flash to replace Nikon SB-24s?

I am wanting to sell (or trade) my 2 Nikon SB-24s and get 2 older Canon flashes so that I can use a ST-E2 to fire them all when doing my photo booth...can anyone tell me the difference between, say, the 550 and the 430? Are there other models worth considering? Thanks!

550 - can be master/slave. has pc sync, can use external battery pack. bigger in size then 430.
430 - can only be slave. no pc sync, cant use external battery pack. less power then 550 (about 1 stop). if you gonna use it in a photobooth. get whichever one that cost less. they both are fine.

johnlo wrote in post #12288409
550 - can be master/slave. has pc sync, can use external battery pack. bigger in size then 430.
430 - can only be slave. no pc sync, cant use external battery pack. less power then 550 (about 1 stop). if you gonna use it in a photobooth. get whichever one that cost less. they both are fine.

Awesome. Yeah, all I need is a slave, got 2 580EXIIs and can't see needing more. Thanks!