Agree re. diversification. Hilton's footprint does play a big part too though as you say. Personally - I like SPG but their property choices are far smaller here in the UK - those they do have tend to be extremely pricey. Hyatt are pretty non-existent, Marriots are pretty poor. Carlson have some reasonable options in Europe with fairly good points earn/burn rates (although no credit card unlike their excellent US one), Accor are very strong in Europe at the budget/mid-range end, but sadly pretty rubbish elite benefits. IHG also pretty good coverage and previously very easy to earn points with (less so this year), elite benefits extremely poor though.

Overall I still like the elite benefits on offer with Hilton and their prices are pretty good. Just spent 270k of my pot - managed to get some quite nice redemptions in FL at $500-900/night spending 50-60k a night so around 1.5c/point which I'm pretty happy with. Now to work out where to spend next! I'll probably still retain a semi-reasonable stash as some of the European redemptions in the 30-40k range are still not bad value.