Preacher, Transmet, Scalped, Hellblazer.
Co-host of Get Valiant, a Valiant Comics podcast.
I love it. One of the best things Steve Gerber had done in comics.
If we're throwing in minis, might I suggest Mutuk Wolfsbreath, Hard Boiled Shaman, my favorite undervalued Vertigo mini? (Thought I was going to pimp Enigma, didn't you? Don't have to-- everyone already loves Enigma.)
Crossing Midnight, by Mike Carey. It's not old, but it is really, really good. And very underappreciated.
Hellblazer and House of Secrets are my top favorites.
American Vampire - just finished vol. 3 and Sean Murphy's art is top notch! Haven't seen such a good artist in a long time. Story was good as well, but you can't beat nazi vampires, can you?
I haven't but you have me intrigued. Was it published in HC?
EDIT:
Found it. Little pricey, eh?
http://www.amazon.co.uk/Joe-Barbaria...qid=1415126386
I guess it depends on what is meant by "old" but these are the Vertigo titles I've enjoyed thus far:
DMZ
Scalped
American Vampire
Trillium
Fables
There are also a few that people swear by that I just couldn't get into:
The Unwritten
Sandman
Invisibles
Epic things: "TOPANGA" (GHA), Jaxson & Zefferson (PRO), Lucas (SHEL)
These are generally considered good reads as well
Astro city
Ex Machina
The Authority
Pre-Vertigo though.