For me, it depends on the jobsite conditions: if I'm looking for production, without a lot prying eyes (owners, designers, architects) and the electricians are on my keester, I go with the drill and jig saw set up. Works fine but looks sloppy before the electrical cover plates are installed.
If I'm on a job where my cut-outs are going to be exposed for a while, I go with a router and template. Just looks better to the (usually) novice laymen inspecting the job as it progresses.
I still get folks who admire an intricate 4 or 5 piece crown buildup, but on the same job question the outlet openings because they look rough (prior to covers, of course).
Dan