I think that it depends....
If you want a knife with the best blade-steel around, but not so impressive handles, then Spyderco makes some of the very best.
The Endura, Delica, Centofante III, Native, Native III, Atlantic Salt, Pacific Salt, Salt I, Rescue series (and others) are practically impossible to beat.
If you want a knife with very strong and substantial handle construction, but not so impressive blade-steel, then Buck and Camillus and Case make some strong and affordable knives--but the blade-steel is'nt that great (usually 420 or 440A).
There is a company that offers a somewhat happy median between blade-steel and stronger handle construction:
CRKT.
Not all of CRKT knives are that great, but there are a few gems if you look carefully--like the Carson M16 line, M18 (now discontinued), and M21 line.
You can get the M16 with AUS-8 and an aluminum handle, with the Carson flipper, and the Lake and Walker safety (LAWKS), all for a good price.
And the fit-and-finish on them is very good.
The CRKT Elishewitz E-Lock series is also very nice.
And here's something that will probably change the whole situation:
Spyderco will soon be releasing the new Endura and Delica, and I believe that they will have steel liners and all screw-construction and top-notch blade-steel (hopefully at an affordable price).
Handle strength, premium blade-steel, and affordability equals the perfect folder!!!
Good luck and happy hunting,
Allen.