I was originally interested in getting the Diamond also. I go the Omnia instead and I think it was the right decision for me. The screen is bigger (3.2 compared to 2.
so actually has more room for information then the Diamond does.
The omnia has the capability to have 32GB (8GB internal storage and a 16GB mSD card) of extra storage while the Diamond from Sprint maxes out at 4GB.
The camera is a 5MP auto focus with LED as compared to a 3.2MP auto focus camera.
The Samsung is customizable but not as much as the Diamond. Hoefully Verizon will release a full ROM soon and we might be able to customize ROMs just like the Diamond.
Verizon unlimited data is $29.99 on this phone. There is a $45 plan also but you only need this if you want to use Verizons' wireless sync program.