I think it's misleading to 'rank' drugs in a ladder in terms of addictiveness - I don't think it's so simple. What one person loves, another may have no interest in. But more than that, I think even on an individual level your wants and needs change over time. Certain moods or events may make you crave more than other times, or crave a different substance, and as you move through life there may be periods that differ greatly from one another in terms of your lifestyle and the choices you make regarding drugs. Finally, it's impossible to compare. How can anyone really tell what someone else is feeling, or possibly say for sure that their addiction is stronger than someone else's? It's all subjective.
Ultimately when it comes to your life the most important thing is what you feel, if for you heroin is the most addictive drug for you then that's true. I can understand wanting to hear other people's experiences with the same drug so you feel some hope - that other people can understand what it's like, that other people have been through it and come out the other end. I think a lot of people here (me included) will definitely agree that heroin has an allure that can be so hard to ignore.
What are your plans for the future though, are you hoping to get off all drugs, just heroin, or reduce your dose? I grapple with that feeling too, of thinking about going my whole life without ever feeling that high again, and it does feel unbearable sometimes. I don't think there's an easy answer, I think part of beating an addiction is accepting that unfortunately, it's true, you wont ever feel that heroin high again, but coming to terms with that and realising that doesn't mean life will be bad. It's a hard one, for sure. One thing I have noticed after quitting an addiction is that, over time, the cravings or thoughts of the high lose their salience. You can remember, intellectually, what is was like, but you can't remember it in that physical, all emcompassing way you do when you're using and you're craving. It becomes more an abstract thought, one that doesn't hold so much sway anymore. I wish you all the best.