Idk, I think that really depends on what you're looking for. Playing through most of both series, I can't really say which one has the better games since they pretty much just offer completely different things.

I think marketing is an issue. VIII was very successful because they made it sell by revamping the menu, adding voices, a symphonic soundtrack, as well as a demo with FFXII. If they play their cards right, XI might do similarly.