Chip Quick is very low temperature solder for removing stubborn parts, but it's very expensive to use as general solder! You get a couple ounces for $20, not exactly a bargain.
https://www.digikey.com/produc.../SMDIN100-ND/8681826
Look on Amazon, they have a good price on one pound rolls of Kester 63/37 Rosin Core solder. It's $23.99 for .031 and $24.95 for the .020, shipped free if you have Prime.