My dream bass in in my closet waiting for its next gig on 12/16 - a 1988 (89?) black Ric 4003. I set the intonation, bridge, & truss rods on it when I lived in Nashville in 1990, then moved to DC, MN, WI, & back to MN, and it's still PERFECT! It sounds glorious, and it makes my fingers do things they never could before (and still can't on other basses).
If that doesn't count as a dream bass because I already have it, then I'd say a Rickenbacker 4003 Tuxedo bass to complement my black one. I think the Tuxedo was a limited edition white color scheme with black highlights they released one year in the mid 80s? I drooled all over the floor model at Knut Koupee the moment I laid eyes on it. And then it went away and I haven't seen one in person since.
Not my first choice as a metal axe though. Bottom end (though SO beautiful) doesn't penetrate enough to compete with metal guitarists who would rather render us meaningless with their massive closed back 4x12s & tuning all the way down to Hell itself (half of them are frustrated bassist wannabes who got demoted to guitar!), plus drummers on the cranked-up kick every 12 nanoseconds. Ricks sound fantastic when distorted though, and that's the only way I'd see them as a good metal bass.
(Seriously, props to my metal guitarist friends! Y'all have had your laughs at your bassist's expense though - you know you do that! A little good-natured payback is all I'm after.)
I like the bottom end of my OLP Stingray for metal (and man, does it record well), but any old P-bass would do nicely, a la Steve Harris. (And I do mean old. I don't know what it is with the newer Fenders & Mexi basses. Their bottom ends just don't penetrate like the old Fenders. Did they switch to a different wood? Is it wood aging?)