I had a Tele set that sounded pretty good. Not phenomenal but it was a big upgrade from the shitty 90s Epiphone pickups the guitar came with.
I had a Strat set as well that sounded ok to me, but I'm not a Strat guy or good judge of anything Strat.
If you can get them cheap, go for it. If there's not much difference between a new set and used Duncans though, I'd go with used Duncans.
Another cheap option is Bootstrap. TDPRI and Gearpage folks love them. I ordered a set for a Partscaster recently but there's a 4+ week wait so it will be a while before I can test them out. And I need another neck for that project, I used the one that was on it for a partscaster my son and I put together.