I’m reading Cunliffe’s Britain Begins at the moment. In the Viking section he contrasts how the Vikings fared in England and Ireland respectively. It’s worth reading while bearing in mind his intention is to give the big picture. Any how, his point is that warlike Ireland was full of very experienced warriors while relatively pacific England didn’t have enough. Duffy, who is a medievalist, covers the same ground from the Irish and Norse perspective in more detail in his Clontarf.
Heather looks at the issue in detail in his Barbarians and Migrations but includes Francia plotting the movements of the Great Army between all three theatres. It’s in the section on Viking expansion and is well worth a read.
As you suggest the main things to consider are social structures and there military potential and the historical record so far as we have it.