Cialis stays in your system for 36 hours, the longest of the ED meds. It is also what my uro prescribed for penile rehab, 5mg daily. So far after close to 4 months post op, not enough wood to start a fire. Apparently though that's not entirely unexpected or unacceptable since the presence of a PDE5 inhibitor is beneficial for long term penile tissue health.
Of the three, Cialis has fewer side effects for me and I like that it has a lasting effect. Prior to my surgery my uro had me on 5mg Cialis and tossed in a few 20 mg for fun. For a day and a half just the slightest breeze would raise the flag full mast, my wife wasn't amused, I loved being a teenager again.