I like GolfWrx. Better BST by a mile. Better club building knowledge, and the tour WITB are genuinely fascinating to me. Also I've been there since 2009 so there's some inertia.
I have only recently discovered MGS, and I like it too. The 2019 ball test is possibly the most interesting thing I've ever read pertaining to golf equipment, and the MTBX in my signature is there as a direct result of the test.
I think the "fully rounded" internet golfer will gain things from both forums and neither experience should be left out.
However, it's weird how I play to a +1 with an 8.5 driver with a 6.5TX Smoke Green @120mph on GolfWRX, and a -8 with a 9.5 with a 70S Ahina @105mph on MGS!!!! LOL.