Queso Fresco varieties
What are the differences in flavor between the different types (salvadoreno, centroamericano, mexican) and brands of Queso Fresco?
And are there other differences, like how they melt perhaps?
My favorite brand of Mexican-style is Los Altos Queso Fresco "La Cubeta". It's made with whole milk rather than skim so it has a richer flavor and mouthfeel. More about it here,
I've not tried varieties modeled after other countries', so can't help you there. I'll mention that Mexican queso fresco does not melt. It will soften a bit on heating, but that's as far as it goes.