If your question has been asked once on the forum, it's been asked a thousand times. You will get a plethora of responses that offer differing opinions, observations and preferences because everyone has different needs and wants and wallets. So, your question should not be "what's better" but rather "these are my accommodation requirements while at Oshkosh and this is what I'd like to spend per day, how can I best fulfill these?"
Hotel rates within 40 miles of Osh go up 2-2.5 times-very expensive. If you go to Green Bay(50 miles-a 45 min. drive) you will get the everyday normal rate. You will then need a car but those rates in GB are normal as well. Dorms from what I've read here are quite reasonably priced but may not/probably don't have private bathrooms or AC(get's real hot & humid that week). I don't have any info on residences
Once you receive all the info here based on your requirements, you will be better equipped to follow up with your own research.