If I had to choose three, I'd have to say:
Darth Beyer
Sennheiser HD-650
Shure E500
I have no need to try much of the other "high-end" phones, with the exception of (4) Stax Omega II, HE90 "Orpheus", UE10Pro's (you try, you buy) and ATH-L3000, if given a higher budget. The UE10Pro's would more than likely replace the Shure E500's. The other's; depends on the higher end phones attributes. IMO, one pair of high level, analytical cans, should be more than enough, the rest should be for fun. Portables are essential and required, but given the high dollar value of the Shure E500/UE10Pro's, I'd be to reluctant to travel with high dollar phones, so I'd make an exception and pick up some Shure E4C's to err on the side of caution.