SRA No Clean Tacky Flux - 10cc

It's tacky and it's flux - win!

It is as described; it makes beautiful quality solder points and is just as good at removing solder from the board completely with a little vacuum or some copper braid. The only thing I'd question is the "No Clean" - it does need a little isopropyl to get rid of the excess, and if you don't do it at the time you'll end up with a sticky board even a week or more later, but I've never used flux that didn't need a bit of cleaning afterwards, and it's such a minor detail that I'd still choose this as my best in class for SMD rework, or even through-hole where it still shines.