Captain Britain is very powerful now, he's like class 90 or so, I don't remember him being that strong. He was never really a pushover, but from Excalibur I don't remember him being that tough.
I hate his costume though, I wish he'd stayed in his Otherworld garb, with the cape and amulet and sword Excalibur (although he gave that up to Kelsey, but he should still have a sword to complete the look).
i think captain marvel is physically stronger than britain, he has the strength of hercules, now marvel hercules is class 100, but i dont know dc hercules. plus, captain marvel also has Solomon's wisdom, , Atlas' endurance, Zeus' power, Achilles' invulnerability and Mercury's speed. britain doesnt have that.