I'm sure any 50/50 to 60+/40- Rosin Core is good. I have pretty much used these over the years. Alphasonic/Archer(ie, Radio Shack)/Other. I do have some with like 2% silver. Most of mine is 10-20 years old as I kept finding a spool here or there (or pocket pack) where I fixed something for people. I actually am about out, and need to buy some.
I'm just asking out of curiousity.
Also, I use liquid and rosin flux, seperate, if I need to.
I am well aware NOT to use acid core. I know what that is for, and it's not electronics.
What about lead-free electronic solder, I somehow got some of that, but don't use it.