My favorite mech to mimic real world scale are the Macross Plus mechs but I can appreciate the super robot over projected hype machines which has captivated creators and the general audience to imagine wilder power wielding abilities.
My middle of the road mech that combines real world applications and fantasy is Gasaraki.
The outlandish mech powered to infinity and beyond within my standard of believability is Escaflowne.
I’m sure that the forums have a breadth of knowledge when it comes to this subject matter, what is yours?