pool.gold is most definitely a scam. They have had roughly 25% of hashrate since day 1 and barely pull 12-15% of blocks.
Looks like some sort of Selfish Miner attack or Block Withholding attack.

Suprnova works a-ok.

I stopped mining BTG and sold all my coins altogether though. I just do not trust the project anymore, and don't see its added value to the ecosystem.