The French side is steeper and more dramatic than the Spanish side, but it is incredibly beautiful. Granny gears are a must! It rained most of the two weeks we took to do the ride, but we heard that the Spanish side can be sunny and dry when it is raining in France. Perhaps, being flexible about the route and giving yourself plenty of time are your most important considerations. Also, French side has longer, less steep climbs going up the mountain heading west from east. Example, col de Mairie Blanc (a real PIA coming from the west but relatively easy from the east).