You're going for status with multiple hotel chains.

You want status with one chain that has extensive coverage. The battle there is between IHG, HH, and MR. Since you've already stated that you're keeping top status with IHG, there's no need to look at HH or MR as a second program.

For second choice, you can go with a program with thinner coverage. That allows you to go for Hyatt or Starwood. I'd recommend one of those two. I find Hyatt the better of the two chains and would go with them. Both Hyatt and Starwood offer lifetime status, but Starwood is much easier to reach.
However, if you travel to Europe a lot, I'd opt for Starwood over Hyatt - Starwood has denser coverage in Europe.
You can get a Diamond Trial from Hyatt or a Platinum Challenge from Starwood.
And both Hyatt and Starwood are easier to reach top status than Marriott; both require 25 stays or 50 nights. I hit top status with both with 25 stays each.

I wouldn't even consider CC; not impressed with their product.