I have used so many brands of fert over the last 20 years that I can tell you from my experience it is best to learn to read the label and understand some basic chemistry about plant nutrients and you will find what works best for you. There are too many variables and availability to answer this question with (I like this because:(. Hibiscus generally works well with a 3-1-2 ratio fert with a good range of micros. Epsom salts for magnesium if not in the fert you're using.
Hope this gives you something to work with.
Happy Growing David

I have used Space City Hibiscus Fertilizer from yardgeek dot com. I have also used fertilizer from hiddenvalleynaturearts dot com. They used to have a time-release fertilizer I really like but I don't see it on their web site now; they do have one that you mix into water though.

If you just have one or two hibiscus, it's easier and cheaper to just go with whatever is local that fits what David said.