It all depends on what you want out of a pistol. If you want a gun that is modifiable to have a superb trigger get the 75B. The older 75's with no B or the Shadow models are even better. If you want a gun that you can improve upoun but you are not a trigger snob get the Omega. Each one works and is reliable and dependable. The action and the parts available to improve them are the largest difference. Either is a great choice depending on your needs and expectations.
Sight options are the same for the 75B or Omega. They are no better or worse for the stock OEM sights from the factory. The later model Omega's have the P-07/09 rear sights that give a little longer sight radious so you might think of that as an improvement.
To add to SP01shadow’s comments, for me it also depends on which feels best to you. The Omega has an upswept beaver tail whereas the 75B does not. If you decide you want upswept beaver tail and not the Omega, the 75 SA, SP01’s, Shadows, and (newer) Stainless models have an upswept tail and the classic trigger design.
Of course if you really like the Omega, get it. It won’t be your only CZ anyways as they seem to multiply
Dots on the Omega are a little better imo, slightly larger, and like Shadow mentioned, longer radius. I like the upswept tail and different hammer, has been a very smooth shooter for me, especially now that round count is over 600.