I personally like FTP (I use WSFTP), but people say I am "old school'. I work in the
tradeshow booth displays design field, and the file size on tradeshow booth display designs can be 200 plus MB. The last thing one wants to do is start over if your transfer crashes at 98% complete, and with an FTP program, you can resume where you stopped instead of starting all over again. Not everyone has FTP, and for those that don't want to get an FTP program I recommend yousendit. I also just tried dropbox based on a friend's very strong recommendation, and it's pretty cool too.
But as for me, I'll stick with FTP.