Have you set up relationships with your potential JV partners already? If not then your JV approach may well fall on deaf ears!
I've found that just approaching a potential partner and saying 'Hey, I've a great product that I want you to promote so we can both make a mint' doesn't get you anywhere. Most experienced affiliates hear this a hundred times a day.
JVs work only when they are true JOINT Ventures. Strike up a friendship. Offer to help someone with a problem they have. Find out what their strengths and weaknesses are and let them know yours too.
A true JV is where two or more partners cover each others weak areas with their own strengths. This may be as simple as "I've got a product but no list" and "That's OK, I've got a list but I need a new product". But usually you find it goes deeper than that and that relationships grow because kindred spirits find each other.
So, with a relationship like that, you won't have to worry that your product is better than your partner's. Because you will both be working on it together.
If all you are after is affiliates to promote your product then all you have to do is make their life easier. Set up a sales page they can use, a set of emails they can send out, banners, short reports they can brand, I'm sure you know all this stuff.
No one minds selling a good product that is easy to sell because all the hard work has been done by somebody else!