I've been keeping fish for 15yrs & have had fluvals & eheims at the same time (different tanks)and have had nay bother with both.
I'm currently only running 1 big tank now with 2 x fluval 404's & I have to say I love them. They have a real good tap design that seals itself with just 1 lever & clips in to release the flow. They have a manual primer that seems a doddle to operate, about 10 pumpos and all flowing.
Haven't got a top end eheim so can't compare but am happy with what I've got.