Another vote for VTM. I tried J37 at a buddies place, It doesn't suck but it wasn't as versatile as the Slate's VTM which gives you 1/2" and 2" tape emulations that actually sound like tape.
i love the J37, specially on bass...you can get a lot of grit with the j37. The slate is awesome...i use it more in the mix bus than on individual instruments.