I'm partial to the Akeda dovetail jig (especailly it's dust collection). I know many woodworkers swear by the Leigh, considered top of the line.
However, I just went to www.porter-cable/jigs and found the
Porter-Cable 4212 12" Dovetail Jig
It's cost only $137 at Amazon. It's smaller, less capable cousin, the 4210, is only $100.
BTW, the videos at www.porter-cable/jigs are pretty good.