They are competitive … if you compare to equivalent accounts at the high street banks. These are probably the main competitors because like Monzo, they provide the ability to have your current account and savings account under one roof.
There will always be specialist savings banks (e.g. Marcus) and the odd account at high street banks (e.g. the Natwest account you mention) that will beat it but I don’t think you have to be market leading to class as competitive.
EDIT: For example, see this comparison I did of easy access ISA rates between Monzo and the main high street providers. Monzo is among the best.