I've got all three. A 55" 4K OLED, 40" 1080P 60Hz Triples and a Vive. Vive is best for immersion, 4K is best for resolution and triples are currently the best for the combination.
VR will be the only choice to make once resolution and image clarity improve. So maybe 2nd or 3rd generation headsets. It's very difficult to explain just what VR adds to immersion, as their is nothing comparable on a flat screen. It's really something you have to try.
4K obviously looks the prettiest but you really need a big screen to get anywhere near the immersion of triples or VR.
Triples are probably the best compromise, and it is a compromise, at the moment. I'd say my 1080P triples are a little to low resolution wise, 1440P should be your aim.
Another thing to consider is what the games you play support. I play many more sims that support VR than support triples properly. And running triples on a game that doesn't correctly support them is just not worth it IMO. I'd much rather play the game in VR than on unsupported triples.
Currently given the choice I play in VR particularly as I have just got a motion rig and VR along with motion just takes my sims to a whole new level but I understand why people feel VR is not quite ready yet.
Personally if I was looking to build a new rig at the moment I would wait and see what happens with VR. If it's going to be a while before 2nd gen headsets are released it will probably be worth going 1440P triples but if it's only a year or so until 2nd gen VR headsets it might be worth picking one up.
Also check out Mr Pix's website for his journey to achieve immersion. It might help you decide.
http://www.projectimmersion.com/index.php