I'd go up and over. I hate drilling 2x4 walls. You need a nailing plate on every hole with a 2x4 wall, unless you drill it perfectly centered, with a 7/8" or less hole. You can drill that corner easily enough, and just put in a nail plate as you'll have to start the hole near the outside edge of the 2x4. I'm assuming an 8' or 9' ceiling height. If the ceiling is much higher, my opinion may change. Until 2x6 walls became standard in new construction, I never drilled horizontially unless it were just a couple of studs. Even now I hate it. I had an employee that is a 40 year electricain that would drill every 2x4 stud around the house rather than go up to the ceiling, if he had a choice...