My fountain pens leak as well. Doesn't matter which one I use, Montblanc, Parker, Caran d'Ache, Waterman, Lamy, Rotring... The leaks are not severe, but holding area always has some, leaving inks on my fingertips.
You may want to check on the inner cap seal. I don't know about the others, but Montblanc might be able to do something about that.
The caps screw or use friction to connect to the body of the pens, with the cap covering the area you hold, the section. In many pens, there is an inner cap that seals over the nib and against the end of the section. It is intended to keep ink leaking into the cap from getting back on the section, but they don't always seal very well.
The caps screw or use friction to connect to the body of the pens, with the cap covering the area you hold, the section. In many pens, there is an inner cap that seals over the nib and against the end of the section. It is intended to keep ink leaking into the cap from getting back on the section, but they don't always seal very well.