Why is a "first seen" rule is used to pick a side in a honest split, instead of deterministic criteria? I was just thinking, why nodes pick the first block they see when there is an honest split, instead of picking, for example, the one with the "best hash" (number further away from the difficulty cut)?

Deterministic criteria like that would allow the entire network to quickly know which block wins, and everybody would then build on top of that block. Much less hashpower would be wasted on the dead branch.

Unless there's some risk/problem in it I'm not seeing...
for example, the one with the &quot;best hash&quot; (number further away from the difficulty cut)?
Deterministic criteria like that would allow the entire network to quickly know which block wins, and everybody would then build on top of that block. Much less hashpower would be wasted on the dead branch.

If you see that you are very likely going to win on account of the deterministic criteria, whatever it is,  then you can withhold announcing your block while you attempt to form a successor and announce your prior win if you see a competing block show up. This would give you an advantage over other miners who behave honestly (and even if everyone does it, it would continue to give larger miners an advantage over smaller ones).