They have 5x10s too. With 2 of those you would only need 2 extraction fans, and have many other benefits that you wouldn't with multiple smaller tents. Then again, there are many pros to having multiple tents too.
With the big 10x10, you would have room for all the equipment to go inside (dehuey, etc), and can even put another smaller tent inside that one for veg, and to help keep the whole tent warm 24/7... Just one big tent with one environment to deal with instead of multiple ones, and needing to buy all the extra equipment and trying to dial each one in. I would probably just build a room before I got anything bigger than the 5x10s though. Or just use the basement as is, but dress it up better or add a few temp walls or something. Something about huge 10x10 and bigger tents seems ridiculous to me, lol. For the price of some of them you can start framing solid insulated rooms that size..