Montblanc pens are decent. But, if you look at other brands of pens, Montblanc can be seen as a poor value. Thus, I would say, the best pieces from Montblanc are standard 146 and 149 pens. The value in the pen is in the size of the feed and the size of the nib. Larger nibs are generally "bouncier" or more flexible and have better writing characteristics.
For instance, the Guggenheim model we both like, that has the same size nib as the 146, which has a 6mm feed. The 149 pen has an 8-9mm feed and thus an even larger gold nib.

4mm feed with the standard Montblanc nib; 146 model with a 6mm feed with a large nib; and a 149 model with a 9mm feed with an extra large nib! When I say size of the nib, I'm not referring to Fine, Medium Broad; I'm referring to the actual size of the gold material.