the krank rev 1 is an amazing amp for very heavy tones, they are perfect for metal, they also have a very good clean channel that you can still slightly distort for some cool tones its one of my favorite amps but sadly too expensive for me. The jvm is great for a hard rock/classic rock tone and will get you as far as a heavy tone but not as far as the rev1, at least by itself. overall both amps have good clean channels but the jvm is better for more hard rock tones and the rev1 is better for crushing metal tones. If your looking for the hardcore metal tones you might also look at the krankenstein+ or a mesa/boogie triple rectifier. If your looking for the rock tones Marshall's are great and you might want to look at a jcm2000. By the price of the two amps ur comparing it looks like this amp might be one your planning to keep for awhile so be sure to do as much research as possible and try out as many different amps as you can.