Polymath is strictly worse version of Ambisafe's Orderbook.
They are not even first with regulated tokens idea since Orderbook holds patent for this stuff.
https://www.newsbtc.com/press-releases/orderbook-announces-one-kind-regulation-aware-protocol-tokenized-securities/

Also unlike Polymath they start with private SAFT round instead of shoving it into everyone's throat with overrated commercial budgets. You can ask about the private round on their email or in support channel in Telegram and maybe you will get invited.