After using Stan's NoTubes sealant exclusively for years we have switched completely to Orange Seal, in our experience there is nothing better on the market. It is slightly more expensive but better in every other way.
This is the newer Endurance version, engineered to maximize longevity. Enabling riders to go 4-6 months between refills.
Proven to seal large punctures up to 1/4″ and perform under varying temperatures and altitudes.
26/27.5/700/29r wheels usually take 4oz per wheel. Plus and Fat bikes take 6oz and 8oz respectively.
Here is an an in-depth review on SingleTracks.com