I would say that depends on you and your plans for the rifle.
If by even money you're talking $900 plus, I'd get the Mark V. You can sell the Mark V and get your investment back. Not so if you spend $900 on the Vanguard
If you're wanting pride of ownership (fluff according to some) go for the Mark IV.
If you're talking $600 I'd say get the Mark V cause you can use it and then sell it and pocket two, three or more Benjamins.
If you're wanting to get "Attaboys" from Big Stick, or worried about 9 lugs get the Vangaurd. LOL
However in the real world, I've found it much easier to sneak up on a vanguard for +/- 5 benjamins than a Mark V.
and with a fair trigger and out of the box accuracy with factory ammo.............
the Vanguards are hard not to like.......
Best,
GWB