Kratom is my "opioid" of choice as far as regular usage goes, simply because I find it to be so mildly addicting that it's very easy to maintain. While I've had my variety including IV hydromorphone on a couple hospital visits, been prescribed percocet and vicodin several times, had my fun with OxyContin, etc., I've never had habitual use of any other opiate besides pods. I most certainly have a tolerance judging from the 20mg of oxy that I got negligible effects from the other day, however kratom still gets me off proper. A 10g dose with some OJ, downed in one shot, gets me feeling euphoric and 101% anxiety free within ~20 minutes, and sometimes almost too high within the hour depending on stomach contents and batch potency. Usually after dosing on kratom, no matter what time of the day, I feel happy and euphoric for the rest of the day. Re-dosing isn't normal practice with me and I don't feel like it does much anyway. I try to limit myself to not using more than every other day, but even that is a habit I'd like to reduce.
Having said that, if I can get my hands on poppy pods, that is by far my favorite opiate simply because of the ultra low cost per dosage and the inhumanly long time it lasts. Back when I was using pods about 1-2 times a week, a good ~17g dose of pod tea would keep me highly euphoric for at least half a day, and glowing big time for the rest of it, usually well into the next day. My eyes would remain pinned for almost 48 hours. For less than the comparable average cost of two 5mg percocets, I could either keep myself QUITE high all weekend, or share with a friend and get blitzed together all day. GOD I miss that stuff...