Do you fly? If you care about spendypants flying and travel, you would have "diamond" status or whatever on any of the majors at $250K/year spend. That would be cool. An AMEX travel card would have some neat options for both flights and hotels. If flying was a major appeal (you live in a city with a hub airport, like to travel last minute a lot, value perks), then the airline card plus AMEX card would be the most fun.
For a true mustachian, there is a fidelity product that gives you 2% cash back to an investment account. That would put the most in your pocket over time, without chasing sign up bonuses or travel rewards. I think that is the highest cash-equivalent reward available.
Generally, where you get above the 2% threshold is if you redeem for luxury, non-mustachian travel things like first class. If don't care about that, I would get the best cashback card you can.
Also, for a while, the business cards had categories where you could get 5x points on an advertising spend, and 3x on gas or whatever. Since advertising was a major part of my biz expenses, I got one of those cards to match to that account. I think Chase phased that out, but it's worth looking into.
Generally, as a biz owner, the highest best use of your time is not chasing points. But it's fun. I'd go to a more CC specific forum like flyertalk or something for ideas.