I'll second the Kester recommendation, the stuff is a bit expensive but if you've used bad solder you know it's worth it! I'm using Kester 275 on the bench and have been very happy with it, and as it's a true no-clean flux, it's a bit less messy than Kester 44 without much performance difference (lead free vs lead differences are real still- Lead-free is still not as easy to work with, but the world went lead free so my bench did too). You can find some comparisons here (since kester's website is down currently for some reason) https://www.jameco.com/Jameco/Products/ProdDS/2188246.pdf