If you still have RAF time, I'd get lots of combos (anything you might want to play, down the road) to 60th.
And then use your RAF granted levels, before RAF expires.

Once you have every combo you might want to play.
Or your RAF time expires...

You can focus on one team at a time.
Which gets you the most time between having to repeat an area.

Or you can bounce between teams.
So you always use rested experience.

Either works, and is a preference call.