My 2 cents:
Symbol: NES as in GeNESis. This way we could refer to Genesis coins as "Nesies".
Decimals: Indiferent. Not sure about the implications of having more or less decimals.
Supply: This is a tricky one. Many investors, youtubers, twitter influencers and many crytocurrency guides recommend to look for coins with low supply. If the coin also has a use case they are called GEMS. Still, multiplying the supply X10 leave us with a 160,000,000 supply which is not crazy high and way below other Billion supply coins, but Genesis will no longer be a low supply coin. Another option is to reduce the supply further, but as Jackson said they might need extra coins for development. A potential solution is to reduce the supply even further, lets say 2,000,000. Give holders 1 NEW NES for each 10 OLD Gens and keep the extra 400,000 Nesies as development funds. This will put Genesis under the radar of GEMS chasers and together with the dividends given to holders no doubt investors will be interested.
At the end of the day, I thank the chance that the devs are giving the community to have our say. I am really happy with the direction the Genesis is taking and by all means go with the plan of increasing the coin supply if you think that is the best way forward.