So, with any combination of PODs after... we'll say after Charlemagne's death, create an alternate list of the 5 greatest powers and their niche. (greatest army; greatest overseas empire and navy; size as buffer; greatest eastern/western/northern/southern, etc)
My Five Powers are determined from a POD where the Byzantines successfully reconquer Anatolia after 1176 under Manuel Komemnos and he is succeed by Bela-Alexios of Hungary after 1180 creating a PU between Hungary and Rhomania. This Hungarian Dynasty last a few generations and is relatively stable, the sacking of 1204 is avoided, the Mongol and Timurid invasions are rough but ultimately the Greeks are able to reconstitute Anatolia culturally back into their sphere after the 1400s.
Through the following centuries the Five major powers of Europe (more specifically those parts affected) have been:
1) Rhomania/Romania: OC the continuation of the Roman Empire has continued to be the primary power of the East Mediterranean, influential in Italy, the Adriatic, the Levant and Egypt.
2) Austria: A major power from the 1400s to the 1800s despite it NOT acquiring Hungary and those eastern lands due to Roman survival. Austria turns attention west into the HRE and culturally similar German lands without sinking resources east. Still vulnerable to Napoleon and ultimately succumbs to his armies but Prussia has been nerfed due to centuries of Austrian hegemony. After 1800 this power is replaced by...
3) France: My reuse. Largely as you were until Napoleon, who I consider a true military mastermind and great leader despite his flaws. I can still see him trouncing the Austrians and without Prussian help of any major decisiveness, Britain and her remaining Allies are at a great disadvantage. On top of this the Polish Commonwealth and Hungary could be sympathetic allies of France...
4) The PLC: This guys won out good in this turn of events. Poland gobbled all the lands of the Teutonic Order along with Lithuania and due to a near perfect balance of power between Poland, Hungary and the HRE was mostly secure on her western front and thus was able beat Russia back in the East. It could potentially usurp Russia's position and reach the Pacific.
and 5) ... not Hungary actually, they were influential sure but a secondary, regional power at best and were contained by Great Powers on all sides which incidentally along with natural barriers and competent defence kept them sovereign following their release from the PU with Romania.
No. 5 is a hard one to discern, I haven't really left much room for it since France and Poland have frogmarched across continental Europe establishing two liberal, meritocratic superpowers, ironic for an Autocratic Byzantine POD!
Maybe others can suggest me a No. 5 for this scenario?
Not withstanding that Great Britain still exists and probably still grabbing clay on every other continent....