Depends on what you use your phone for and if you take quite a lot of pictures but not into selfies then I would take the 830 if the 930 is not available to you. As the 830 has a 0.9 mp front facing camera and you have the benefit of pureview tech, OIS, mSD card slot, qi wireless charging and glance.
On the flip side if the 930 is available to you and you can live without glance get that instead as you will be able to enjoy everything the Lumia Denim update will bring along with 1.2 mp wide angle ffc.
The 735 has a decent camera but nowhere as good as the 925 and you lose the dedicated camera button along with the capacitive buttons. Personally I would say it is a step backwards .
However everyone uses their phone differently so if you mostly take selfies and confined to a budget then get the 735.