i would go wit the bmw.dont now what ur price is range is like, but i would go wit the 745! dont qote me on this but im not to sure if the 5 series come in a v8, and i no thats what u said u wanted!
Stay away from VW, any repair will cost you a small fortune. The older BMW just looks like someone that couldn't afford one when they were new.
I would actually go with the Lincoln LS, repair costs aren't too bad since its a domestic.
I would go with a lexus ls400 or 430. they last forever and are v8 and huge. and the older ones aren't too horribly expensive. after all they are toyotas underneath all that leather and pearl paint and air ride stock. but that's me. but then again I am a toyota guy. and hondas on occasion. (can't beat 200 bucks for an engine in a civic)