Best water-proofing agents?

[Scooter]

What's the best waterproofing agent for full grain leather boots? The boots are knee high Caterpillar brand, used for: yard work, worn to work, & running errands in the snow. I don't use water-proofing but I have a friend who is trying to decide between Obenauf, Sno-seal, Aquaseal or Nikwax.

[newforest]

That's a good question. When it gets wet, I'd rather switch to knee-high rubber boots, but then I work right in the water fairly often. Lately I've been thinking to own two pairs, an insulated pair, and an uninsulated variety. The insulated type make a great snow boot. All while also owning good leather boots (again two pairs; big toes for flat ground, and narrow toe for steep stuff). At least my feet won't be changing size any more.