If you're doing the short ribs recipe, as I did recently, I mixed about 2 tbsp molasses (not blackstrap) with regular honey. Worked just fine.

Which do you want to use? They function the same, but clover honey is much milder, and so tastes sweeter than buckwheat. It really depends what you are making and if you want a strong honey flavour. For a spice cake, I'd go with buckwheat, but if it's something light, like a panna cotta, buckwheat will be very strong. If you're recipe calls for buckwheat, go ahead and sub clover, but not always the other way around. Hope that helps!

Buckwheat honey is a dark, rich, less sweet honey. If you're going to sub, I'd probably mix molasses and clover honey to get a closer approximation.