I submitted 5 LORs to my recruiter with my package.
1) University Professor I had a lot of classes with.
2) Former supervisor at aeronautical company I worked for and former AF enlisted (20+ yrs of service).
3) CFI I did my PPL with and current ANG O-2, C-130 Nav.
4) CFI I did my instrument with, USAFA grad, O-3, CE in AF.
5) Current co-worker at aeronautical company and former AF enlisted (15+ yrs of service).
All of these people knew me well and though they might not be O-8s or anything it didn't stop me from getting selected (OTS). Don't worry if your letter writers aren't impressive or have 30 yrs of prior service, just make sure they know you well and have something constructive to say about who you are and why you should be selected.
Also make sure you letter writers use spellchecker.