I have a 76s and an etrex Legend (same as the vista but w/less memory, and no compass or altimeter). I really enjoy both units.
I love the small size and weight of the etrex. I can carry it easily in my shirt or jeans pocket, and its very easy to be discreet when using it in public (e.g. urban geocaching). On the downside, the screen is so small I have to take reading glasses along on all my adventures, which sucks majorly. (I've already lost a pair of prescription lenses this way)
The bigger screen and external antenna connection make the 76s a much better choice for using in a vehicle or airplane.
Much has been made of the patch vs quad-helix antennae. In my (admittedly short) experience it is not entirely clear-cut which works better in all situations. I think the patch is supposed to have better reception of satellites directly overhead, while the quad-helix has better reception of satellites on the horizon. I have had the 76s lose reception while up against a steep canyon wall and all the satellites on the horizon were on the "wrong" side of the canyon. I sometimes take both units caching, and I haven't noticed that either is uniformly better.