The GS 3 is comfortable to hold and feels smaller than the likes of the one X due to the more ergonomic design.
If you want a smallish device then look at the HTC one S, in the same league as the GS 3, one X, nexus 4 etc. and it is cheaper by a good bit.
The GS 4 will be out around May/June.
The only phones coming out soonish that will be worth looking at will be the xperia Z and HTC M7 (pretty much a HTC DNA/deluxe/butterly), however, they have 5" screens so will be pretty big.
EDIT:
also the razr i is worth looking at.