the 5.5" bowie blade is definitely your best choice. the 7" is going to scare the crap out of everyone around you, and more importantly, is incredibly unweildy. I even have trouble opening packages with my 5.5" stiletto maxx, which is why I also carry a leatherman micra.
i prefer the stiletto simply because the blade looks nicer, and of course it's appreciated in value (I bought a few maxxes back when they were $120-$130). The bowie blade however is definitely much more utilitarian and useful.
if this is going to be used hard, I would recommend buying a lone wolf tactical ranger (the 4.9" blade version) instead. Although the maxx is an excellent knife, the blade is somewhat on the thin side and in D2, which makes it prone to chipping if it's going to undergo hard use for anything besides slicing cuts.