I just need that little more convincing that it's hardware can still match up to the S4
The reason that your GS 2 ran much quicker/smoother than the desire HD was partly due to hardware but most importantly software, GS 2 was the first android phone to have hardware/GPU acceleration and really blew every android phone away at the time.
All android phones improved with ICS (as long as the hardware was good)and every phone has benefited from JB (GN is really smooth and fast, same league as the top end phones).
The GS 3, one X, S, XL, nexus 4 etc. are all in the same league for performance (minor differences that aren't worth worrying about imo) and I doubt that performance will be "much" different with the one and Gs 4. The manufacturers are just bumping the specs up for the sake of it now really, 2GB RAM and quad/octa are not "required" for a fast/smooth phone, the software is what they need to concentrate on (although its not like they can improve the performance much more as it is already plenty fast!
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)
As for which phone to get between the one and GS 4, I feel it will come down to preference once again
one:
- audio overall
- build/perceived quality
GS 4:
- battery life (octa version, if the big little thing works as described)
- SD slot/removable battery
- better NLED
Software, design and screen are personal preference.
Battery life on the one should be better than the droid DNA, certainly shouldn't be any worse.
Camera is too hard to judge really since there isn't much on the GS 4 and the one seems to have either a hardware or/and software fault which is producing very variable results, however, I think once it is fixed/improved we will see better results "overall" as the hardware in the one (regarding the camera) in theory is better than the gS 4 (gs4 is using the same sensor as the xperia Z), certainly won't beat it in low light/dark conditions anyway.