After many great years with RT6 i had to switch after i started using the car for HPDE, as it was shearing down too much at the track. As oil temp increases, oil pressure decreases proportionally. With the RT6 i had about 20psi at idle, street driving temps around 180F, but coming in after 20 minutes on track with temps ~ >220F i'm closer to 5-6 psi @ idle. High Temp High Shear rating on the RT6 is about a 3.7 IIRC.
I have since switched to M1 15w50 which is 4.5, still has reasonable Zinc/Phos and is cheap...at the track I'm only seeing a small improvement in shear over the RT6 (almost 7-9 psi @ idle @ ~220F). HTHS can vary widely between oils even at the same viscosity rating. For comparison, Redline 15w50 is rated at 5.8 HTHS. RL is super shear stable, and and performs much better both in the lab and in the real world. Ultimately my car is still a street car so it's been tough to justify switching to RL at double the cost.
OP: usually when shopping oils i'm looking at manufacturer specs and virgin oil analysis and used oil analysis reports and talking to people. Specifically looking at HTHS, zinc/phosphorous/moly content, viscosity @ 100*C, detergents like boron, calcium, magnesium.