Unfortunately lead-free solder is a lot harder to solder with; it just doesn't flow as nicely. Companies doing it in an automated way have long figured it out though.
This is why hobbyists are often still using leaded solder, particularly outside of the EU. But also in the EU, because it just flows so damned nice.
I find SAC305 to wick into joints faster than leaded solder does, provided you have quality flux in the solder.
If you get the cheapest lead-free solder you can find on Amazon it will be bad.
Doubly so if you have a non-temperature-controlled soldering iron. Too cold, and it won't melt effectively. Too hot, and exposed metal will oxidize rapidly.
