Let me tell you how and why I choose Nikon D5100.
I was disappointed with my Sony hx-1 photo quality, the grains in the photo was unavoidable in all situations. Also the DOF was quite OK. I used Sony hx-1 more than a year.
When I was feeling to move to DSLR but all time i had a same thought "which one". Again its not a easy job as we are investing so much of money and buying any entry level DSLR is not at all right. That has to be right one.
I refereed this site more for comparing cameras [link].
I ended with selecting 2 major manufactures as I don't want to take any chance with other companies. you know these CANON and NIKON.
(Feature):- (For 5100 ) vs (For Canon)
Significantly lower noise at high ISO :- 1183 ISO vs 793 ISO
Much better image quality :- 80 vs 65
Much better color depth :- 23,5 bits vs 22,1 bits
Much more dynamic range:- 13,6 EV vs 11,5 EV
Continuous video focus:- Yes vs No
Has in-camera HDR :- Yes vs No
Much less startup delay :- 500 ms vs 1500 ms
Video autofocus :- Contrast detection vs None
Longer battery life :- 660 shots vs 440 shots
Larger sensor :- APS-C 23.6x15.6mm vs APS-C 22.3x14.9mm
Better boost ISO :- 25,600 ISO vs 12,800 ISO
More focus points :- 11 vs 9
Smaller :- 127x96x78 mm vs 133x99x79 mm
Slightly more lenses available :- 169 lenses vs 162 lenses
Shoots slightly faster :- 4 fps vs 3.7 fps
Slightly less shutter lag :- 273 ms vs 283 ms