See payment gateway comparison for an up-to-date comparison between gateway options.
The "SCA" in "Stripe SCA" stands for Strong Customer Authentication. This means it includes Secure 3D anti fraud functionality to make transactions more secure.
Any new functionality of Payments2Us will only be added to "Stripe SCA". Currently a big difference is Apple Pay and Google Pay are only available with "Stripe SCA".
One key user experience difference is "Stripe SCA" requires users to press the "Next" button before the credit card/payment details section will show.