What's your favourite gear ratio?

http://sheldonbrown.com/fixed.html#bigsmall

I ride 48x17 on fixed. No hills where I am. Use my geared bike for longer rides...

Currently creating a cheap pub beater for my brother for xmas. I'm not changing the crank so im stuck with either a 42 or a 52. Not sure of the best combo for him. Its flat near him too, although he may use it to commute.

Im thinking either 42x15 (75.6) or 52x19 (73.9).

can anyone see any issues??? Still havent decided.

OK, gear ratio aficionados, I recently inherited a 44/18 gear ratio on a second hand bike I bought. It's pretty lumpy where I ride, but even so, it feels massively under geared. It must be improving my pedalling technique, but...

So, it needs changing. I have a proper track chainset with a 49T track ring that I could use, so do I go 49/18 (I'd still need to buy a new sprocket and if I can't splice 2 track chains together I'm likely to need a new chain too) or do i go 45/16 (I'd need a new chainring and sprocket, but could definitely use the existing chain). The benefit of 45/16 is that I can then also attach a 16T freewheel that I have in the spares drawer to the fixed/free hub just in case I fancy some singlespeed action in the future.

In summary the question is 49/18 or 45/16 given that the cost of either option is likely to be similar. Any mechanical advantage/disadvantage for either ratio? I don't do wicked skidz. I don't much care for the aesthetics of the 49T ring if that makes a difference. For what it's worth I used to ride 53/16 when doing "big gear rides" when training for TTs, but I did have to avoid the steepest hills completely on that bike. Reckon either of the 2 gear options will be ideal for my all round riding I'm planning. Thanks!