On the Kenwood side, NX-5000 is the only current product that will do Phase 2.
There was one older product that did Phase 2, but I think it was 7-800MHz only.
EFJohnson has a few. VP8000 is a nice multband portable that was recently released and is getting excellent initial reviews. Plus, it's about half the price of an APX-8000
Might help if you were a bit more specific of what you are looking for.
Truth is, if whoever set up the Atlas system did it with having other manufacturer radios on the system in mind, it should not matter what brand you use. Radio systems running just the standard APCO P25 phase 2 standard setup should accept any radio running APCO P25 phase 2 system.
The only real answer that matters would be that of the system admin. If they are going to limit radios to models they've confirmed/tested on their system, they'll be able to tell you:
Which one will work
Which one they will support
Which one they will program to work on their system.