Both are basically weekly hundred+ hour motion pictures. Incredible production values.
Where they split for me is the tone, writing, and acting.
LOST's tone can be serious, then it can be incredibly funny. Dark, then light. BSG's tone tend to be dark all the time. Almost suicidally dark. Can be a bit much over time. Also it is very soap opera-y. Overwrought to the point of being eye-rolling. Takes itself a bit to seriously when it doesn't really have the chops to back it up.
The writing on LOST is also superior. The twists and turns. Wrapping up and solving things that happened several seasons before, in a very surprising way. Making the metaphysical mumbo-jumbo almost make sense. BSG attempts to do the same thing, but it all seems half-assed in comparison.
As far as acting, it's not even close. LOST is superior in every way. Battlestar does not have anyone that compares with Ben. Even the weak actors like Evangeline Lilly have raised their game. BSG has some horrid actors. *coughkatiesackoffcough*
Carlton Cuse/Damon Lindelof>>>>>Ronald Moore














