I was looking at the same choices when I built up my tourer back in 2009. I wound up going with 105 due to cost; Apex would've needed to be special ordered from any shop I talked to, so I committed to scouring the internet and buying parts piecemeal, out of the clearance sections of many websites. It was a lot of fun, and a LOT of work.
Really, they're of similar build quality, and the only difference is the shift mechanisms.
edit:
For the record, my bike build was an entire 10-speed drivetrain. I've got Shimano brifters, cranks, and derailleurs, but a SRAM cassette and chain