Greetings:

As someone that has been at one point (or another) highest tier on NW, DL, CO, AA and UA (non-revenue based), in my (very humble) opinion, the best top-tier status for elite treatment and benefits (i.e. not considering any "hard product", on-board service, route structure etc.) of the non-revenue based frequent flying tiers is EP on AA. For me, it was without question the one where I felt that I got the best treatment consistently. YMMV on this one for sure.

I do miss being an EP.

Safe Travels