If you're looking for something that is not another RSA style OTP solution check out LoginTC. https://www.logintc.com/docs/connectors/

The approach leverages the smartphone for what it is, a connected device with rich user experience interaction. https://www.logintc.com/docs/platform/multi-factor-flow.html

Full disclosure: I'm a co-founder at Cyphercor the builders of LoginTC.