Many Vivitar 283 has very high trigger voltage (mine is 250V). It does not have manual variable power setting. Its head can tilt, but can't swivel. I wouldn't recommend it.
Sunpak 322s has only 2 aperture settings in auto mode, GN is 80.
I recommend: Sunpak 36DX (European name of 444D), 444D, 422D, 383 Super (or the clone Quantaray Q383). They all have GN of 120 (except for 422D having GN of 100), 3 aperture settings, and 5 variable power settings from full to 1/16.
Some of the models (422D for sure) have the "power saving" feature: the flash turns itself off after 5 minutes on idling. You may not want this feature for remote flash.
36DX, 4xxD are nice because you can use a Sunpak dedicated extension cord (model EXT-08). The flash is remote, but the sensor stays attached to the camera's hotshoe:
For Vivitar, I recommend Vivitar 5600 or 3700. 285HV is solid but does not swivel (285 without 'HV' in the model name may have high trigger voltage). Here's a Vivitar 5600 with a simple flash extension cord (the bracket and handle are recycled from a non-working Sunpak 522):
Pentax AF280T is very popular, but its GN (I think 90) is slightly less than the Sunpak units above, and it has only 2 aperture settings in auto mode and 2 levels of power settings in manual.
If you feel patient and lucky, try to get a Nikon SB-24, 25, 26, or 28. They are powerful, solid, and have a lot of features.
None of these supports p-TTL. But the auto mode works just fine. In fact, I mostly use Pentax 540 + K10D in A mode. I use p-TTL mode only when I absolutely have to (e.g. HSS, trailing curtain).
If you like hammer-head flash units, I can recommend some too.
Last edited by SOldBear; 02-22-2011 at 02:29 PM.