So I tried to do the whole, "use whatever codec you like" thing, and it's not working out. I converted everything to ProRes 422 and things work much better. BUT, I was wondering what Premiere likes best, codec-wise. I know FCP liked the ProRes codecs best, but what's best for Premiere?
Not sure whether you're referring to the footage codec or the sequence codec.
I've had mixed results using camera-native codecs. Transcoding to ProRes or DNxHD before offline is definitely snappier, but for small-ish jobs I often just bring in whatever MPEG2 or 4 the camera recorded in. This depends on your machine, of course—the CPU, GPU and disk(s) speed.
I always use either a flavour of ProRes or DNxHD. I render as I go, and then when it comes to exporting, I select 'use sequence previews' and the export is pretty much as fast as the disks can handle it. This is analogous to the old FCP7 'export as FCP Quicktime movie' option.