When I was detoxing from alcohol in a clinic they gave me the benzo "Librium" every 6 hours. Librium is a rare benzo but used for withdrawal because it has an extremely long half life, I'm talking several days long. You also don't get high from it because it has an extremely long come up and come down if that makes sense.
To answer your question klonopin would undoubtedly work the best, the Xanax and Ativan have a quick strong punch and short half life, you need the exact opposite! The half life of kpin is 30-60 hours, perfect in your case. The Xanax and Ativan will just get you high for a short period then you'll just want to keep redoing, bad idea. The klonopin will slowly come on, relax you a little, and then slowly wear off, and it's long half life will still help with withdrawal even though you may not still "feel" it's effects. When I was in detox they gave me the benzo every 6 hours, and at every 24 hour mark they would half the dose and keep continuing that cycle until the dose dissipated to nothing and you went a day with nothing at all.
If you were withdrawing from alcohol or benzos I would say you absolutely must go to a clinic because it can be EXTREMELY dangerous going cold turkey at home. I still would recommend going to a clinic to detox your opiate problem but it's not as necessary as alcohol/benzo withdrawl would be. Detox at your own risk!