I honestly think morphine formulations are the best specifically opana ER even with its low BA as it has very little side effects (raised heart rate, slow pounding heart feeling, heavy warm head feeling, nausea, and other neutral to negative effects) at the level it produces sedation and analgesia in my opinion. There are not any hydromorphone ER in the states apparently so that leaves you with morphine or oxymorphone. I prefer opana ER for nighttime use while using a codeine formulation during the daytime where I use a half 10/325 mg hydrocodone every 4 hours if needed. I wish there was a hydrocodone ER, which will not be out until the end of the month although the OC er should be just as good if you need it as well as the only ER codeine and related compound formulation available that I know of.
Although these recommendations are for pain management and not abuse. Hell if you have roxi ER just abuse those to boost the other medication you take properly if you really feel the need to abuse the medication that you should be doing your best to not raise your tolerance so you can use it effectively at a lower dose for a longer time. A good recommendation is to eat a fatty meal when you use the opana as it is supposed to raise the BA to 30% just 10% under nasal administration based on a study by endo, which will make it more effective and I found to be able to enable me to get to a recreational nodding dose around 30 mg oral where I use about 10-20 mg a night in lines of about 1-2.5 mg.
Trust me though... There are better things to use for recreational while with this compound/drug is better to respect and use as medication or in my opinion at the tail end of psychedelic trip to help to prevent the body from becoming tense making it easier to sleep. I am sure you have heard it 100s of times, but trust me addictions are no joke and easier sneak up on you and bite you in the ass and does not let go for a long time.
Edit: To the person below I honestly recommended to stick with opana and just eat fatty foods when dosing as I find opana to have less negative side effects while morphine takes just as much as opana to work, but causes more side effects as well as in my case was very ineffective used all ROA besides IV/IM.