I would like to know which one to get on the shimano 105 5700 Groupset if using the chainset 170mm 39/53 option.

Any help please.

Thanks

12-25 is pretty well the standard.
A 12-27 will give you that extra little help with a climb, as I see your running a standard chainset.
Simple as that.

I don’t mind admitting that I might get a 27 for next winter.

My new bike’s got a 12-25 on it and tbh I just think it’s bloomin silly. But then I’m not much of a roadie. So you should take this all with a pinch of salt but the only 3 thoughts I’ve ever had on the gearing selection are 1) Could do with a slightly higher gear. 2) Could definately do with a few lower gears. And 3) I’m fed up of double shifting.

Proper roadies/crossists may disagree.

Main difference is that my middle aged kness prefer the 12-27

OP what gears are you used to?

Thanks for the advice.