Molly has more features and it's developed by indie devs.

For one thing, it still has the option for an additional fingerprint lock to open the app.
Sure, my phone itself is locked anyway, usually.
I still like having the second lock built into the app itself for the odd time (however rare) that I hand my unlocked phone to someone.
I know they're not snooping into my signal messages while I blink or misclick on a notification or whatever.

It may not be a big deal for some/most but I like that feature and I can't imagine that's something that needs much upkeep once initially implemented.

I'm sure it's not the only feature, but it's one I use often.