I have directly tried Beyer DT880, T1 and T90 models with my Crack.
The T1 is my headphone of choice and is only made in 600 ohm.
IMO the DT880 (pretty sure I tried the 600ohm version) is good, but I'd choose the HD650/600 over it. The T90 is very good for those who like bright signatures and is similar to (but brighter than) the T1. That said, the T90 is not as good as the T1 IMO so if there is budget available it's well worth the stretch to the T1.
Of everything I've heard, I think my order of recommendations would be:
- Beyer T1
- Senn HD800 (second only because of personal preference, not quality of can)
- Beyer T90 if you can do bright signatures
- Senn HD6X0 (either model depending on taste)
- Beyer DT880 600 ohm