I played DCS a little many years ago. Then i got a Track IR and thought wow this is neat, probably added 50hrs or so to my total DCS playing time but eventually lost interest. Then I got VR and now have been playing regularly for years.
TrackIR is probably best if you just want to play DCS as a game, shoot the most things, be the best you can on multiplayer. If you just want to play a game that's cool, your allowed, different people want to do different things.
VR is best if you want to play a simulation, feel like your as close to the real pilot flying the real plane as you can be. When i was a kid i always dreamed of flying these planes and VR is the closest thing to the real experience, looking at a moving picture in a frame doesn't compare.
Also a few people in here talking about VR performance, i play on a 1070 mini card with often terrible frame rate, in my low res CV1 and still play all the campaigns. I don't find it to be a big deal tbh, still totally amazes me every time i jump in.