That's EASY. I'd take the ABS in a new york second. Having killer abs is a hell of a lot harder than getting big arms.
For the arms it's easy, just take a shitload of vitamin "S" and eat like a fucking pig.
But to get killer 6-pack abs you MUST diet religiously, do hours of cardio and have the will power of a Mother Teresa.
I've had 18 inch plus arms and didn't even hit them that hard when training. The ONLY time I've had a 6 pack was the time period of 7th grade to the 12th grade and I was doing 4 sports and not eating hardly anything.