Larfleeze wins. He has the entire power of the Orange Light. The guy is a Parallax level threat. He destroys high level planet busters like the Guardians and torches through the GL Corps. and Controllers.
Thanos has no actual feats. Knocking back Galactus is not a feat. Especially in what seems to be a low to no gravity environment. Regardless it didn't harm Big G whatsover, didn't even phase him. He was begging for Galactus not to turn him into fried Thanos pudding when his shields held up to one momentary blast. Notice Galactus says that one additional blast will destroy the shield and Thanos with it. Also notice he say's admirable tech. It's not Thanos himself but a piece of tech creating the field.