tin solder

What is your preferred solder?
I've bought 3 on aliexpress and two local.
All 5 had different characteristics.
What would be your coise?

Thanks in advance

I useKester 24-6337-0027 Solder Roll, Core Size 66, 63/37 Alloy -https://www.amazon.com/gp/product/B07KWDYNLV/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
I don't need to prepare or flux or anything - just solder directly with 100w iron. My oldest packs are 3yrs and the solder has notcorroded or caused any long term issues.

Use 60/40 rosin core based standard solder. I use 300W high perf soldering pen with heavy duty copper tip. It makes sure i only need 1 second to solder and nothing else.
100+watt is generally needed and a tip that have big mass. I dont buy tin on bay like sites. Thats something i buy from proper vendors so i get proper stuff! Its such a difference.

You should never have to grind on the cells.

I have done videos showing how easy it should be to solder. Heat, tinn and then it flows directly.

Here's a good run down of solder types:


And flux