honestly, just get 2 rings - 1 for you, 1 for your follower - you get 20% of the XP bonues from your followers ring added to you. so you get 35 on you, about 7 from your follower, and another 5-6 from a leorics signet on your follower if you want.
then do the most efficient MP level you can do quickly, mass kills, quick zone clears - dont go for bragging, get the most kills, and least deaths for whatever MP level you can handle with 100% efficiency. then your paragon levels will start to fly by.
farming rings is a massive waste of time, cause of the sheer amount of time to farm just 1 ring, and the extremely low chance of getting a good ring.
just accept the fact that the rings gonna suck, but atleast its better then leorics signet, and free, and use it. get them paragon levels.
farming hellfire rings is just a good way to slow down your paragon levels, and get less loot per hour. get what you need, and move on.
dont get suckerd into the blackhole of hellfire rings.
What we've decided to do is just do our regular runs, and then at the end of the run kill keywarden of the act. If he drops the key, awesome, if not, oh well. Whenever we have the keys, we go kill ubers, and then go back to farming normally. It's a pretty good system because you're not going to get sick of just farming rings specifically.