I've got offers from both Mesa and Compass. I'm not basing my decision on ZEDs, but I'll be commuting from Ireland quite often. Do
Mesa and Compass have ZEDs with the following?

Aer Lingus
British Airways
Virgin Atlantic
Flybe
KLM
Lufthansa

I also have an offer from ExpressJet but reading through the threads here I don't think I'll take that.

As I said, the commute won't be something I'm constantly doing, but ZEDs on the carriers above would really help.