Naptha pulls will give better yields than heptane but will pull more gunk and from what I've been reading, MHRB is getting gunkier and gunkier since my friend stopped working with it, but then it may be the tendency now to do heated pulls. Heptane will pull a much cleaner product but possibly leave behind a lot of (maybe unknown) alks if one doesn't later extract with something less selective.
One has found that the nicest way is to extract with heptane and then do a couple of pulls with toluene and evap both. The heptane gives a crystal that recrystalizes into glass shards in one pass and the toluene goo can be used as is or washed with naptha, heptane, or whatever to give varying ratios of jungle and NN.