Lansky, dmt aligner, gatco edgemate. Witch one has best clamp, and witch has best stones/hones. That being said can you use stones/hones of one brand with anothers clamp?
I'd say it 'depends'.
I have 2 Lansky sets (the 'Deluxe' and a diamond kit), a Gatco diamond kit, and a DMT Aligner w/Magna-Guide (used with DMT's Dia-Fold hones). The more current versions of the clamp on the Lansky seem to be better with smaller blades, like those found on traditional pocketknives. DMT's clamp doesn't handle small blades as well, but it's probably easiest to set up & use with most other blades.
As for the hones, I think DMT makes the best diamond hones. Lansky's hones are smaller, and again, that can be useful on smaller blades. They afford a gentler touch with fingertip control. If looking to get a Lansky, I'd get the diamond kit; the standard hones in Lansky's other kits can have troubles with more wear-resistant steels like S30V, especially when trying to re-bevel or do any other heavy grinding.
The Gatco hones are larger than Lansky's, and are also very comfortable to hold & use. The guide rods for the Gatco allow a longer reach, which is helpful on large/long blades, like large kitchen knives. The Gatco clamp is very similar to Lansky's, though I've had some issues with mine, in not being able to grip some blades as tightly. The way the clamp's surfaces are finished has a big influence on how well they grip a blade, and my Gatco clamp seems a little slippery with more polished blades (this is one aspect in which the Lansky clamp has greatly improved). The 'grip' issue can be helped by taping the blade and/or the clamp, so there are usually ways to work around it.
And yes, you can usually use a clamp from one system, with hones from another. Just make sure to stick with one version of the hones from start to finish, and not 'mixing' them between brands. They won't all work at the same angle in the one clamp, because of differences in the way the hones are set up with their guide rods.
David