The Nexus 5 will be more of the same: stock vanilla Android. I've used stock vanilla Android with ROMs since December 2009... so continuing that experience doesn't appeal to me. I know it all too well.
The Note 3, OTOH, has features built in that appeal to me greatly: Air command, voice actions, S-pen note taking and automatic transcription into Contacts and texts, etc. Plus all the stuff I haven't even figured out yet!
Vanilla Android or new cool stuff? My decision was rather easy