Generally there are three kinds of roles we have our followers played, DPS provider like Templar Tank, MF/GF Provider like Enchantress, and Buff Provider like Scoundrel. Take this poll and give suggestions to other players at our community or feedback.
DPS Provider: generally to perform this role, we would equip our followers with the items of main stat and vitality. If you choose Templar for your Demon Hunter, then you should give him the Strength as main stat. Some players can stack follower DPS as high as 10K. This would a great help when you are in threaten. Your follower may give the fatal blow to your enemies and save your life.
MF/GF Provider: Even though you only get 20 percent of their total MF/GF, it helps a lot as high as 20 percent MF and 10 percent GF. As I never get really supporting legendary items since the launch of Diablo 3, I began to pay attention to my Enchantress MF/GF. Now the equipment for the Enchantress is really low. I bought The Grand Vizier of 381 Intelligence, +221 Vitality, +44 Extra Gold from Monsters and 44% Better Chance of Finding Magical Items at only 500K Diablo 3 Gold. For the ring, you can choose Oculus Ring. But remember that you can only equip this kind of ring at one finger. I did not know this and bought two. Now I have to resell one.
Buff Provider: In Scoundrel skills, there is a skill to increase critical hit chance by 3% for the player and the scoundrel called Anatomy. Besides this bonus, scoundrel can be a ranged support as well. This would mean a lot especially for the melee attackers like Barbarian and Monk. For Demon Hunter, I think they would prefer a Templar to tank for them. There are some skills of Scoundrel to stun and blind as well. This would help the players a lot.
Every follower has their unique points. Of course, you can combine the DPS and MF/GF for your follower. Having a clear idea that what kind of roles does your followers play would help you build your follower to the best. Take the poll and keep tuned.