The value proposition of the AMEX biz plat increases if you have a legit business and can tax deduct the annual fee; $700 pretax becomes $420 posttax, perhaps even $350 if you live in a state with high tax, if you buy United travel bank for personal travel this brings it down to $220 (or even $150).
Between the Dell credit (buys my tax software), $50X 4 Hilton credit, 35% back (stopped using this, using AA miles more), and centurion lounge access, I can probably get $200 out of this so still see (minimal) value to not cancelling the card. Well actually I did cancel it recently, but got a NLL offer a few months later…