It partly depends on the make-up / interests of your group:
Huntington Beach is probably the easiest to navigate, with plentiful parking and shops. But it can feel a bit crowded (and full of teenagers) for my taste. Great place to observe the surf city culture (shops, etc) and actual surfing. Nice pier too. And you've got Sandy's restaurant right at the pier (you can just barely see the water from the patio). Reasonable value for food, and a better-than-average beer list.
The Newport Beach suggestions above (Balboa Peninsula / Island, Crystal Cove, Corona del Mar) are all lovely, with high-end shopping available at nearby Fashion Island, and little boutiques on the Island & CDM in particular. Some regular beach type shopping too. And 2 piers. The Stuft Surfer's no longer there at 15th street (it's looked like a construction zone for years - they must've run out of money mid-remodel), so the peninsula restaurant scene has changed somewhat. I think Newport provides an appealing and relatively accessible mix for most visitors. In the Peninsula area, I LOVE Sabatino's - it's in a sort of marine industrial area (boats around, but mostly out of the water awaiting repair or sale or whatever), so it's not really a pretty spot but the food is excellent. They make their own sausage and it's delicious. Pescadou Bistro on the peninsula is fabulous, too, but fancy / expensive.
Laguna feels like a fancy beach town with plentiful art galleries and boutiques. It's probably the most picturesque. If you've seen pictures of SoCal beaches with cliffs, they're probably of Laguna. I don't make it to Laguna all that often because traffic and parking can be nightmarish.
I grew up in Seal Beach, so I'll add a plug for it - it's quieter than some of the other beaches, and easier to navigate / find parking, while maintaining the quaint main street vibe. There's a pier there, too. And a bar with full bottle mimosas for a reasonable price (the Hangout) where you can sort of see the pier / water area.
