Which lead-free solder

[tekfan]

The best lead-free solder to get is the cheapest, dodgiest lead-free solder you can find out of china.
Since it's most likely lead solder with a lead-free label 

Good one! Also true.

[nukie]

You don't have to worry about tin whisker if you are doing hand soldering. The joints are too thick for them to grow. Tin whisker usually grow on tin coatings which means bare RoHS components are the carriers . If you operate an assembly plant, I suggest you look at SN100C if you haven't already, apparently NASA also quite like it... Balver Zinn in Europe produces and sell them under license.

Sorry I don't recommend cheap China solder wire . Get something that you can trust, at least you know what's inside your solder.. rosin or RMA. You don't want plumbing solder which is very corrosive. Most cheap Chinese solder I tried behave like eutectic solder and it felt as if the raw material used are not pure enough, this makes reworking the solder joint difficult. The quality isn't great compared to locally obtained cheap 60/40. It's not worth to contaminate your board with whatever formula they had for making that cheap solder, unless you can trust your supplier with the data composition. On the contrary, cheap China solder paste I tried are actually quite good quality.

Wherever you are located you should be able to obtain proper solder easily. They are not terribly expensive and a small spool last a long time, provided you are using the right size.

[Psi]

yeah, i wasn't being serious