How plausible is a Reformation scenario where instead of northern Germany and Scandinavia spearheading the Reformation (in the sense of breaking with Rome), you have Spain, Portugal, or France leading it instead?
For what it's worth, I think of the English Reformation as a sui generis event - I think England was on the fence IOTL and in most ATLs; it's just that they needed a push in a certain direction (like Henry VIII being frustrated with not getting a son IOTL).
Perhaps a different Habsburg ascendancy? Perhaps the Church adopts doctrines more conciliatory to German burghers and dukes than Spanish tastes?