For me,it starts with the 4 F's:
Fit,Finish,Flow and Feel.
Clean,even grinds,blade-handle ratio,and materials appropriate to function.
I like Balance,and have a thing for book-matched material
(handle scales and bolsters),
but all elements of the knife should compliment,or contrast in a way that feels
right to me (everyone has their own personal 'Right' )
Over and above good steel with good h.t.and good design,
it has to make my hand happy;
it's a tool first,and something that pleases the eye 2nd.
There's a song by the Northern Pikes that states that some women
"ain't pretty,they just look that way",and knives can be like that too.
(Good from afar,but far from Good)

And,I also consider who made it. How established they are isn't really a consideration (other than the 'comfort factor' that comes with a known maker): a new maker who is a Good person and offers good,honest work will win me over an established maker with good knives who is unethical,and/or a prick.