There is quite a prolific literature attempting to address the relative importance of those factors in the development of thick coal measures.  Although I don't follow this literature very closely, it seems clear that the waxing and waning of ice sheets in the Late Paleozoic played a major role in the climate/vegetation dynamic across Pangea. 

My sense is that evaluation of many of the classic cyclothem successions are likely extracting the most robust signal, in part because the repeated marine incursions offer an important indication of relative sea level (and often its trajectory). 

Here are a few relevant publications that might be a good starting point for further research:

https://www.researchgate.net/publication/279804783_Revealing_the_hidden_Milankovitch_record_from_Pennsylvanian_cyclothem_successions_and_implications_regarding_late_Paleozoic_chronology_and_terrestrial-carbon_coal_storage

https://www.researchgate.net/publication/236004286_Sequence_Stratigraphy_and_Onlap_History_Donets_Basin_Ukraine_Insight_into_Late_Paleozoic_Ice_Age_dynamics

https://www.researchgate.net/publication/277680060_Appalachian_sedimentary_cycles_during_the_Pennsylvanian_Changing_influences_of_sea_level_climate_and_tectonics

Article Revealing the hidden Milankovitch record from Pennsylvanian ...

Article Sequence Stratigraphy and Onlap History, Donets Basin, Ukrai...

Chapter Appalachian sedimentary cycles during the Pennsylvanian: Cha...