The problem with this kind of a poll is that it is an "all things being equal" sort of question but all things are NEVER equal. All things are variable. So what is best is a moment to moment kind of things. A couple of years ago everybody was buying $50,000 SUV's using home equity loans. Then the housing market crashed and gas went to $5/gallon and Ford and Chrysler closed SUV/truck plants. Auto dealers went broke and closed too. Once upon a time the VW Beetle was a $1700 car that got 30 mpg and could hold 4 big people. Things change. Variables vary. Guitars come in many brands, many colors and many configurations and then you can continue to change them all the time you own them (after market add ons, etc).
One thing that is absolutely certain: a guitar is worth exactly what a willing seller will sell it for to a willing buyer. At that moment in time that is exactly what that guitar is worth. BUT IMMEDIATELY the value of the guitar changes and the new owner may have entirely different valuation and would not sell it for twice as much or may have to pawn it for grocery money. It is a moving target to say the least.
Generally speaking Gibsons, Martins, Taylors (and one or two other well known brands have consistently superior workmanship over decades (70-100-150 years) and so that translates into value (constantly changing value). Same for horns, cars, firearms, planes, boats ... and some cars.
How do you feel about your Gibson compared to what other guitars you won (or what you see in stores today)? is it worth MORE or LESS? Why? What factors go it to how you feel about your guitars?