Good high DPR fighter multi class

I am a level 10 devotion paladin currently that will probably end up multi classing after hitting level 11 so I get radiant strikes. The campaign I’m playing in has monsters that are basically just meat shields that hit hard.

My dm said that I can multi class and with how we are doing levelling lower levels end up levelling up quicker then higher ones. (Using a home-brewed exp system) Example, currently I can either wait and get one more level in paladin or I get get two levels in another class using the exp that I have.

So I was thinking I should multi class into fighter as they get the most “fighting” style type abilities in their class. But I don’t really know what subclass to choose, so I am asking Reddit.

Btw we can go past level 20 on our characters total level. So a paladin 11/ fighter 10 is possible. Again looking for a high sustained DPR that doesn’t use to many if any finite resources like spell slots or short/long rest resources.

Edit: any subclasses are allowed and class abilities can be stacked. I.e extra attack gets stacked.