CMAccount.apk may cause problems (removed it, then added it again and going back to home was running first time assistant).
Lockclock.apk can't be removed anymore, it causes androidui error at boot (up to M7 it could be removed) because there's no way anymore to disable it. You can delete it, but at start there's at least one message box to close.
I removed lots of safe apps, but no way, I got random bugs :
Apollo, Basic Dreams, Browser, CellBroadcastReceiver, CMFileManager, CMWallpapers, DownloadProviderUI, DSPManager, Email, Exchange2, Galaxy4, LatinIME, Mms, PhaseBeam, VideoEditor, VoicePlus, WhisperPush.
I eventually went back to M7, it caused too many bugs for me (FC at start, random wallpaper errors, ...).
I think I'm going to build a M8 zip with all apks I don't want in a bak folder, add some GApps and some of my apps/data and flash from full wipe, I guess the M8 needs to regarding problems I have with...
---------- Post added at 07:13 PM ---------- Previous post was at 07:10 PM ----------
Oh, by the way I guess I may script a cleaner. It would be easier for me and I would share it with no problem.
Just make sure you've ADB, debugging enabled, USB cable and pop corn