If you want to go forth and back between ZBrush and other applications then there is an amazing tool called GoZ. You can work simultanously in both apps, so you have all the uv-mapping, polygon-modelling, re-topology of your choice.
No export nor import, it is just like you are working in one app:

http://www.zbrushcentral.com/zbc/showthread.php?t=071414

Currently it works with Maya, Cinema4D and Modo (with many other applications soon to come). And since Modo is the best polygon modeler with great re-topology and best uv-tools at all, I am sure the best combination is Modo / ZBrush (you will see them both in the end of the video).

Artists all over the world were excited like crazy as they saw this video (except Max users, because they still have to wait).