... I don't know, the story beats are better in this one, and the whole experience has a tighter feel, but I would stick take the epic moments from Halo 3 campaign over the actual events in Halo: CE.
By and large, Halo 3's battles (and much of this applies to ODST as well) are bigger, more refined, and versatile than any in Halo: CE. This applies to the interior scenes as well. None of the interior combat in Halo: CE (PoA, latter half of T&R, indoors of AotCR, Keyes, The Library, The Maw) come close to interior combat of Crow's Nest.
The Maw, like Keyes, has monster closets. I can't believe I didn't notice them before, but it's nowhere near as bad (thankfully). Even in places where it doesn't make sense, like at the top of the ramps leading up to the engine core.
I'm going through Legendary (sans bandana) for the levels I like (TSC, Halo, AotCR, T&R, 343 GS). Really enjoying it. After I get the achievement for Legendary completion, all I'll have is the co-op achievements, an AotCR achievement, and the "complete a level with three skulls on" achievement which I plan on doing on AotCR. Fun times ahead with the game.