Best backup chain?
I would use Hilton as a backup. Their gold is the best mid tier status and cones with breakfast, Internet etc. they are also quite large comparing to Hyatt.
Otherwise Marriott would be good if they status match you. Maintaining it is an challenge through.
Hyatt diamond has great benefits but not sure about their coverages in EU. It's quite small...
And PC doesn't give you much besides bonus points....