We make our judgment by comparing a set of ideals and elements on a bike. We make our favorite bike by choosing components to our liking, they can be anything from a specific technology, a futuristic look, to a more classic or vintage look. If the idea is a good weather bike for fun, the short ride into town, a shopper, or racer or a solid work horse, it makes the outcome. Most of us have an idea of how a bike should feel when riding, it's very individual. New materials are developed to weigh less and handle a lot of stress, but they are rearly made to last for more than a couple of years, and very few bikes are made to lessen upkeep and replacement of parts these days. I know the differece between steel, carbon and aluminium, and the three come in too many variations and qualities to be generalised. There are very nice steel frames still made, even though it's not the main focus of the marked neither among the competitive sports nor general consumer. I think Reynolds top of the range steel tubes are quite up to comparison with the best of titanium and carbon.
There are lots of not so good components on new bikes, low cost bikes with horribly heavy frames, childrens bikes that look very fancy but weigh more than a 50s roadster (!!). In my mind this is fault of the commercial marked, because there are much better equally low cost alternatives. In these cases, a used bike can be endlessly better in every way, maybe except for the brand new paint.
When it comes to fast and light nothing compares to the up to date racer bike. I love how the top of the range gears slide up and down seamlessly. It's so smooth I am impressed everytime. I also know it cost a lot, wears down and needs replacement parts quite often. I aslo like internal geared hubs, both old 3 speeds and the newer 7, 8 speeds as well as Alfine 11 speed. Sturmey Archer, Sachs and Sram are nice too, some feel a bit heavier than others but quite acceptable even by todays standard. I so get the idea of a light, minimal single speed, but when it comes down to my every day bike I have to compromise. I hate having that dusty or wet stripe up my back all the time (fenders!!), and I like a few gears too.
Regarding frames, I don't mind steel at all, some lugged frames are very nice and are up to speed as far as my standard goes. When it comes to stiffness, flexing and "sluggishness" of the material I feel it's down to the finer points and I can't always afford take advantage of them. Add a geared hub with coaster brakes, or any hub break and it cancells out the finer point by far. I hesitate a bit when it comes to carbon fiber, very light, and cool look, but I worry about all the beating it has to take. I know some have had their carbon frame for years, but I aslo know of several guys who have ruined their very expensive bikes in less than 18 months. Ideally my bike should last a life time with a bit of upkeep, I know it's asking a lot and it depends quite a bit on luck too. On the other hand like to try the new advancement in material and technology, and some times it means a brand new bike, other times only a new set of wheel. I can't have every type of bike out there, but I can have two or three and it allows for a bit of experimenting and different approaches ;-)
My view on what's best is not either nrw or old, but more like it depends on what you want from the components. Top quality is very expensive, ordering custom parts is too, a vintage bike much older than me can often be ideal for my purpose.