Hi shiyaoay!
Thanks to the awesomeness of The Greatness, I was able to find your thread so I can tell you that I am having the exact same problem!
I'm pretty sure your problem lies within Better Cities - Better IC.esp. If you disable that, it should work fine. Problem is, you lack the mind exploding awesomeness that is Better Imperial City. I tried activating the separate districts of the city to see if it would still crash on startup, and so far it only does so when the Market District .esp is activated. Everything else runs fine, which is a shame, 'cause the Better Market District is probably one of quality market overhaul mods.
Edit: So I think I may have found the problem. I tried removing everything that had to do with the mods and reinstalled it using display's instructions. So far, the game actually loads up but I crash when trying to reload my old save, which doesn't really come as a surprise. Creating a new game seems to work fine and the cities work as they should.
However, the Market District seems to have moved down a few steps and there are a few floating objects. I've found the note that says I should change up my load order even though I ran it through BOSS, however not even moving it right before the Bashed Patch seems to work. RESOLVED: Make sure you import the Better Imperial City.esp into the Bashed Patch. Fixes the floating issue.
shiyaoay, did you happen to download the patch from OBC told you to on tesnexus? The one that contains the .esm file? I think if you ignore that and just use the .esm file from Better Cities should get you passed the crash on start up.