B.C. Rich Bich Archtop $249.99:
* Basswood body
* Bolt-on maple neck
* Rosewood fingerboard
* 2 humbuckers
* Black hardware
* 25-1/2" scale
* 24 jumbo frets
* Sealed B.C. Rich tuners

Jackson JS30 Kelly $299.99:
*Bolt-On Maple
*Die-Cast Tuners
*24 Jumbo Frets
*Jackson CVR2 Humbuckers
*JT390 Adjustable Bridge with Strings-Through-Body
*Chrome Hardware
*25.5" Scale

Ibanez RG321 $279.99:
* Wizard II neck
* 3-piece maple neck
* Mahogany body
* 24 jumbo frets
* 25-1/2 scale
* Bound rosewood finger board
* Fixed bridge
* IBZ INF3 (H) Neck PU
* IBZ INF4 (H) Bridge PU
* Pearl dot inlay

Which one is worth it?

OR can anyone suggest another guitar for metal.

$300 is my limit.
Never played any of them but the Ibanez RG321 has a real good reputation around here and B.C.Rich guitars have a real bad reputation around here too. As for the Jackson.. well it looks sweet.
My Gear:
Epiphone SG
Vintage SG
Stagg Strat (With replaced hardware and a Duncan Invader )
Hohner Strat
No name Acoustic
Jim Dunlop Crybaby
Boss MT-2
Boss DS-1
Roland Cube 60
Wires and patch cords and stuff..
For the guitars you listed:

Ibanez > Jackson > B.C. Rich

The RG321 is a great guitar for its price, and it fits nicely in your budget.