CruiseAmerica.com is a corporate chain of RV rental stores. They have a select models of mostly Class C RVs that they rent from.
If you are a first time renter and are reluctant to deal with Private RV owners then you should start with a short weekend rental from CruiseAmerica.com and get a first hand experience of renting an RV.
Once you are comfortable renting an RV then look through the RVShare.com and Outdoorsy.com to look for RVs that suit your needs and budget and have good owner ratings.
Please read through the following article to get a more detailed comparison between the three:
Also refer to following article that compares the RV rental companies: