All things being equal (hypothetical) which do you prefer, XLR or RCA?

By far, the biggest difference between unbalanced RCA and balanced is on long runs of cable.  Short runs of unbalanced work very well.  I use 18-36 inch connects, only.  I have A/B's these on my system. At about 20 feet, I can find a difference if I get totally anal about it. 

This construct of "which do you prefer, XLR or RCA cables" is kind of backwards. Choice of XLR vs RCA (single ended) cables follows the design of source equipment such as DACs & preamps, in which either balanced or single ended designs may be executed for reasons best known to the designer.

true - but there are equipment/system choices that can be made using one method or another ...  thus the question is relevant to many

If you can get your DAC or preamp near the amp there is no benefit from a balanced connection, conversely if you want to drive mononlocks near the speakers balanced is likely the preferred option. In high res systems with short cables my experience is that balanced depending on implementation at worst is more sluggish or in the best of all worlds gives no discernible benenfit. Longer runs, balanced wins.

Xlr vs rca.  No one can tell the difference when runs are shorter.  AB testing impossible due to volumn level changes.

if i had a choice i would go xlr, cause its alot cooler to say i use xlrs.

so go for it

Either.

That's why 'gender-benders' and whatwherewithall exists for your purchasing pleasure.

'That' is all rca....whereas, 'this' is either xlr or 1/4" phone.

Except for the f/o, that's pretty straightforward....

One adapts....*s*