I am running Practical Sailor type test...
I put 1/4 triple nylon on my backstay halyard and 3/16 braided polypropylene on my spreader halyard. Both work fine after 1 year, but the triple line is a little fiddly to get into the flag clips as it tends to snag. A larger clip would resolve the issue, which is minor at best. I generally prefer triple line as I can put in an eye or a back splice with my eyes shut and without tools!