The ESP Guitar Company

Hi guys I currently have a Laney HCM30 amp which sounds ok but I want to update to something to acheive some heavier sounds similar to early Slayer/Metallica/Exodus my budget is about $400-$600aus I was looking at a Randall RG75 G2 or maybe a Marshall VS65R or VS100W and also the Peavey Valveking 112 can anyone help on which will help me acheive the best heavy/thrash sounds ? Or maybe suggest something else. My guitar is a KH-602. Thanks.