In light of this thread I've been looking around online for what people deem to be their favorite bullet for varmints. There doesn't seem to be a consensus - everyone has their favorite pet load and caliber, although there are a few standouts that show up over and over for 22 caliber pills:
40 gr VMax
50 gr VMax
53 gr Vmax
50 gr TNT
50 gr Blitzking
There are some people who go lighter than 40, but there is a lot of love for 40 and 50 gr varmint bullets for 22 caliber.
With good reason. Despite the heavy bullet for caliber craze of more recent years, there are a LOT of rifles with barrel twists more appropriate for the lighter (and shorter and faster) bullets that have historically been excellent performers in 22 caliber varmint rifles.