Use a combination of both.
Just about every olympic lift is a "trap builder." Just the explosive nature of the the lifts, creates a maximum recruitment of the trap fibers (as well as just about every other muscle group, but especially the traps).
If you're not comfortable with the "catch" part of the lifts, just do the high pull version....still a high amount of trap involvement.
Perform cleans, snatches, etc in the lower rep ranges...5 or less (This will give you maximal fiber (and CNS activation) of the traps.
You can then do traditional BB/DB shrugs utilizing higher rep ranges to fully exhaust all the fibers of the posterior shoulder girdle.
Personally, I do snatch grip, regular grip and push press shrugs. Shrugs are like calves...they have a small range of motion and can withstand a beating.
Also, if bigger traps are what you're after, increase your standing overhead press numbers. The traps play a significant role in starting an overhead press and locking it out at the top.
Plus, increasing your trap size will lead to better flat press performance, as the upper back is the foundation in which you press off of, when benching......think tight upper back cue when setting up for a flat press.
AND huge traps look bad ass!