First of all - what magnification? Most common are 4x and I have one of them (plastic and cheap), but maybe stronger one would be more precise?

Which model is recommended - I'd rather go for a new one. It should be sturdy, housing made of metal and lens made of glass, GG friendly, good quality optics. I do not need diopter adjustment as I wear contact lenses. I was considering Silvestri - either 4x or 6x. Are they OK?