It's down to personal taste so much you will get a variety of answers, but I give you an uncommon one. Serrated Spyderco. I do quite a few tasks that will destroy an edge in an instant and it seems serrated blades excel in this as the cutting edge is mostly protected.
Fixed Busse, Cpk, are pretty tough as well as Swamprat. Then there's Fallkniven with its laminated steel. I'd check out some videos of them being tested. There are a lot of good knives out there though.
Best at what? Best built? Best bang for buck? Best action? Best at slicing? Best “hard use” titanium pocket brick?
We get a little context since you said the magic overbuilt word: I recommend you look at the Chris Reeve Inkosi and maybe Umnumzaan and the new Gen 6 Hinderers. Also check out Grayman knives like the Satu.
Fixed blades? There are so many different kinds of fixed blades for entirely differenr roles. Best edc fixed? Best chopper? Best dagger?
1. Real Steel Megalodon 2017. .14” thick, full flat ground M390, great in hand, action on par with $500+ knives. Can be had brand new for $170-$208. One site also has an N690 version for $99.99.
2. Massdrop x Laconico Keen. $139.99-$159.99 depending on handle style. Original design from a highly regarded designer, built by WE. S35VN, .155” thick at the spine, super aggressive ffg primary bevel angle, thin behind the edge. This one has taken over pocket time for a few of us.
Now, let’s throw value for the dollar away and look at the absolute best knife under $500:
It’ll be the Alliance Designs Ray Laconico Jasmine, because ... opinion and preference.