I am not aware of any "optimal" amounts of the forms of sugar you mentioned to achieve optimal browning of the crust. Generally, the conventional advice is not to exceed about 5% by weight of flour. The 5% figure basically represents the threshhold value beyond which most people will detect sweetness in the crust. Too much above that figure can also adversely affect yeast performance. That said, I think it is safe to say that sweeteners like molasses, barley malt syrup (non-diastatic), and honey--especially the darker varieties of honey--are likely to produce greater color in the crust than ordinary table sugar. Each will also contribute its own flavor profile to the finished crust, and you might find that using high levels of any of them will produce flavors that are too powerful . Most professionals use an industrial grade of honey because it is the darkest and has the most flavor (it's also the cheapest).
If you are currently using table sugar and want to substitute one of the other forms, you should keep in mind that you will have to increase the amount (by weight) of the other forms of sugar by about 20%, to compensate for the fact that honey, molasses and barley malt syrup are about 20% water. Theoretically, you should also reduce the water content by 20% of the weight of the honey, molasses or barley malt syrup. I think you will find that for the amounts of ingredients you are using, that amount of water in the honey, molasses or barley malt syrup will be fairly small and not worth worrying about.
You didn't mention the possibility of using dried dairy whey to increase crust coloration. Dried dairy whey includes lactose, which is a form of sugar that is not metabolized by yeast and has a low sweetness factor compared with other forms of sugar. So you will get increased coloration but not added sweetness. Consequently, it can be used with other forms of sugar if you'd like without noticeably adding to the overall sweetness.
If you decide to go with honey, molasses or barley malt syrup, you might want to start at 2% (by weight of flour) and work up from there in 1% increments (using 5% as the upper limit) until you get the results you are trying to achieve.