Diamond Ambassador at IHG, Globalist at Hyatt, and Platinum at Marriott but through the AMEX Brilliant but will hit Titanium soon.
I started staying at Marriott's starting last year, the biggest difference is how many hotels Marriott has in any particular city. It was really confusing at first on which property I should stay. IHG and Hyatt are much more straightforward on what to expect from each brand. The only reason, I find Marriott hard to stay in, is because of price. I guess people pay to stay at Marriott's. The prices are many times much higher for the same level property in many places. Once in awhile, you'll find a decent deal and that's why I'm about to hit Titanium since I found a few good deals but for the most part, compared to IHG, prices are much higher.