What's your favourite gear ratio?

Sorry for my ignorance but I can't get my head around these gear ratios. I'm riding 48-16 at the moment.

What would happen if I changed my cog to 17? Would that mean i would lose speed on the flats but easier up hills?

I'm riding on a freewheel

roughly.

i would say lose speed on the flats only if you can't spin that bit faster when the gearing is lighter. if you're legs are loose (in a good way) then it shouldn't be more effort to go at the old speed.

yes easier up hills