My opinion is that most of them would go east, towards the Black Sea. Gaul and Celtic Bohemia will remain pretty strong without Roman intervention, so while the Germanic tribes may raid these regions, they likely would not permeate into them, or conquer them like OTL.
Instead, they would probably head towards the Black Sea and the Balkans, which would be war torn and out of shape, while still being extremely wealthy and valuably, aka, the perfect target. (There is some precedent for this OTL with the Goths). The Germanic tribes would likely settle in Dacia, Thrace, and parts of the Ukraine, and then consistently raid south into the Balkans. Who knows, you might end up with reversed Slavic and Germanic fates, where the Germanic languages are the ones split between North (Scandinavian) and South (Balkan).
I think later the Slavs would move into what we consider Germany because of the vacuum caused by the eastward Germanic migration.
I also think this gives the Sarmatians a fair chance at surviving as a culture and people along the steppes.
The Huns would certainly be more focused on Greece and the Near East.
What happens later with the Avars, Magyars, and Vikings is hard to say, and greatly depends on the rest of the political world, however it might be shaped.