I have been highest level or next to highest in all four programs for many years...what I can tell you is SPG and IHG are FAR more generous with upgrades than MR or HH. They also are FAR better with redemptions.
Suite is fairly standard, I can't remember the last time I stayed in a regular room with SPG.
We'll see what happens after the merge (particularly with lifetime) but in my eyes SPG is far superior. My only complaint is you run across a hotel in need of updating from time to time.