There are few very good cases for the premium branded phones and i have found Spigen, Diztronic and Cruzerlite's bugdroid to be very good. For some reason, Tudia didnt came up with Z3C's case. But do check.. they too make TPU cases and good ones at that. For a tougher variant, i think Spigen/Diztronic will serve you better.
I purchased Bugdroid variant for another phone from
this seller. The case is TPU and provides decent protection, and will serve your purpose if you plan to put a decent only case. He sells em without any bill, and i am guessing that is the reason for low price. Very communicative, and he has an online store on amazon.in as well. Purchase with coupon if you can and get a good deal.
11 Sony Xperia Z3 Compact cases
As for the phone, cant really provide you with any specific input, but if no other alternative comes by the end of this year, i will get the Z3 compact itself. It is amazing how there is not real competitor for this phone yet.
Sony prolly is planning to shut their mobile phone division, so maybe one of the last few legendary phones from their camp.