Well, rattling this off the top of my head, but I've seen...
1. The Hot Rod, I think $1800 for the full kit.
2. The Vocas, about $1200 for the full kit, and my favorite PL adapter bar none. It has a custom AF100 baseplate, it's quick-release undockable (no need to unbolt and unbuild your rig, I *love* this feature), it's got excellent solid engineering, and it's perfectly pre-shimmed so that the focus marks hit spot-on with all my lenses. I love this rig.
3. The Atomic by Optitek, a very clever and inexpensive design, I think it's $895 for the PL adapter including an AF100 baseplate. The Atomic has the same kind of quick-release feature as the Vocas, but slightly differently; you don't have the ability to float the adapter by itself without the support but you can undock the camera from the mount easily and then quickly swap to a Lumix lens or a Nikon or something. And I actually like the thumbwheel screw for locking the camera to the tripod better on the Atomic than on the Vocas, because the Atomic has a lot bigger wheel. But it just doesn't exude the same feeling of quality of the Vocas. But then again it's noticeably less expensive.
4. The Solid, sold by Birns & Sawyer. Easily the heaviest-duty unit on the market. If you're wanting to use an Angenieux 24-290, this baseplate system is (like the name says) Solid. The PL adapter and support mount directly to the baseplate; everyone else mounts onto rails. And the baseplate seems to be made of cast iron, or something equally solid. :thumbsup:
5. The Letus, I think about $600. The only self-shimmable adapter I've seen in person, and also has a unique top-mounted support so you can have a supported adapter without needing a baseplate and rails.
6. The Ciecio7 with foot, $320. Occupies a weird spot in my arsenal -- I used to hate it, now I kind of love it, even though it isn't depth-accurate so all the focus marks are off. It's just so inexpensive and I love how the support foot fits exactly on my Cartoni or Redrock quick-release plates, so for a lighter-weight lens it provides a supported mount system with (again) no need for rails. Also the only one that really works for the GH2 when using it as a B-camera.
Ones I haven't seen:
7. The Ciecio7 without support foot, about $240. I wouldn't really want a PL adapter with no support under it at all...
8. The $199 ebay unit from... I don't remember who.
9. The MTF adapter
10. The Denz
11. The Ciecio7 with built-in backfocus adjustment. I think HeavyG has one of these and could advise as to how it works.
12. This 16x9 adapter
There's I think at least one more (or maybe even others) that I don't remember or can't think of right now, but that pretty much represents the price range and what I thought about the ones I've used.
I can make a case for many of them, but for the overall winner for flexibility, reasonable cost, light weight, easy dock/undock, and gorgeous build quality, I really like the Vocas.
I like the Hot Rod unit, it's very well built and very solid, and if you intend to permanently rig up your camera into a rails system, I do recommend it. But that's not the way I work. I'm a lens fanatic, and I love the small size and light weight of the AF100, and I don't like (at all) permanently bolting it into some big rig. You may not have the same preference as me, and therefore you may prefer the Hot Rod or Solid over anything else, but ... I just love that it's a little 3-pound camera, and I love love love using something like the Voigtlander f/0.95 lens, or the tiny Lumix 20mm pancake, or especially the Lumix 7-14. And to get to them, with some of the adapters and rails systems and baseplates, that means spending plenty of time with an allen wrench to unbuild the whole rig. And then when you want to go back to PL, you have to re-build the whole rig. Not my thing. I love (love!) being able to quick-dock and quick-undock the camera on the baseplate and into the PL adapter. The Vocas and the Atomic excel at that, and for that reason they really push my buttons and I find them both compelling. The Letus is capable of doing something similar (quick undock from its hanging hook) and the Ciecio7 with foot allows me to do sort of the same thing - reasonably quick undock by removing the tripod base plate or, in the case of the Cartoni, just loosening and then sliding the baseplate backwards. Then you can pop off the PL adapter, slap on the Lumix or Nikon adapter, and go.
I just think the beauty of the AF100 is that it's tiny and featherweight, and building it into some big massive rails/mattebox/follow focus rig, takes away a lot of the beauty of what you can do with that little camera and a Lumx 7-14...
So, read my assessments with that bias in mind, and you may very well prefer a different way of working and would therefore prefer a different style of adapter.