I'm the owner of a Note 4 GearVR. I've tried it, the Note 5 GearVR, and the Vive.
I prefer the Note 4 GearVR to the Note 5 GearVR because the former has a larger viewing area than the latter, and that makes a big difference in the sense of presence you get from experiencing VR.
I prefer both GearVRs to the Vive, because the Vive has a much shallower depth to it. When using the Vive, it kind of looks like you're standing in a relatively small theater with a wall about 10 or 20 feet away from you on which the background is projected. In the GearVR, by contrast, the "end" of the viewing area is much, much further away, and often can't even be distinguished (except in certain apps/games). So the feeling of being in a real space and not in a fake environment is much greater in the GearVR for me than in the Vive.
Also, because of the above, I get a much, much greater sense of scale in the GearVR than in the Vive when looking at huge objects like a mountain or looking down from the air in to a valley. I've had no experiences in the Vive that get anywhere near that. It really always feels like a very small space. For some apps or games (particularly ones where the VR environment is itself a room or other small space) that doesn't matter, but for others the Vive's deficiency in this respect breaks the 4th wall for me and reminds me that it's fake.
Another reason I prefer the GearVR is because it's completely portable and wireless, and doesn't require a beefy desktop to run it. I've taken the GearVR with me on airplane trips, and used it to watch movies on the plane (movies that look pretty amazing when you have almost a whole IMAX screen in front of you, while everyone else on the plane is staring at little 4" monitors in their seats), and I've demoed it to many dozens of people all over the place, including at a beach. You can't do that with the Vive.
These advantages of the GearVR are somewhat counterbalanced by the full-body motion sensors in the Vive. That's pretty nice, but I haven't really played any games or used any apps on the Vive where it made enough of a difference to be way better than the motion detection built in to the GearVR, which can already sense the motion of your head. Often, what you're mostly doing is turning around and looking around, and that can be done well enough on the GearVR.
I haven't tried the Rift, but I've heard that it's significantly better than the GearVR, so if I was going to get a tethered VR headset, it would probably be that. But I think I'm going to skip at least a generation or two of VR headsets until they get much more comfortable, and until the apps and games available for them graduate from being mostly technology demos to being competitive with full-featured non-VR apps and games. The comfort issue is an especially big one for me, as after the novelty wore off, I really didn't want to wear the headset for long as it grew increasingly uncomfortable and just wan't worth the trouble. I've you've never tried VR, though, it is mindblowing (or at least it was for me and 99% of the people I demoed it to), so it's well worth trying, if not buying.