I use lead solder.
And I have my PCBs made with a lead solder finish.

I am aware that the world has moved on. I hadn't done any electronics for some years before starting this project so when I started to kit myself out I had a look around. I couldn't work out what to do on the lead-free front. There seemed to be a whole range of different tin/silver combinations with different temperature requirements, lots of different fluxes etc. As I was originally intending to do only a few small experiments I eventually decided that this wasn't worth pursuing any further. In particular I knew I would have enough problems on the electronics front without having to worry about how good the soldering was. Once the project started to escalate I was already hooked on lead.
I had one colleague say that it was easy to go lead free. But on questioning it turned out he thought it was just a question of using a higher temperature. And anyway it wasn't his problem, he'd just specified lead free. Doing it was someone else's problem.
And I've had several other colleagues/friends say that my choice was entirely sensible. Lead free is ok if you've a factory and/or skilled technicians where you can control the processes. But for a muppet at home it's hard work. And I really really really need good solder joint reliability.

Currently I've just bought my 10th 250g reel. So 2.5kG of 60/40 tin lead solder. Once that has been finished the Megaprocessor will contain a full kilo of lead.

This does mean that the Megaprocessor might struggle to reach the mass market.