IMHO 8" is the 'sweet spot' for jointers. It's big enough to do 99.9% of what I plan on doing. They are big, heavy and stable. Yet, they can be moved without major difficultly. If I need to joint a wide board I can either rip it or have a shop do it.

That being said. If I ever get our dream house and my dream workshop I would love to have a massive ancient aircraft carrier. In addition to my 8". YMMV.