A ~550-piece set from my childhood (90s): 10 minifigs and accessories, end result will fill about a 1-foot cube. Plenty of room for small hands to get in and actually play with it. Construction simple enough you can easily put it back together if it's messed up during play, without resorting to the directions. Exposed studs everywhere for easy adding-on.
A modern ~550-piece set, also from a line aimed at kids, not one of the adult-aimed models: 3 minifigs, fills 1/3 cubic foot at best because 450 of the pieces are little 1x1 and 1x2 plates or similar. Finished set's too small for even kid hands to get in and play. If it gets messed up more than a very tiny bit, you'll probably have to re-build from scratch, because the construction is... very CAD, I guess. All surfaces clad in smooth bricks if at all possible, making adding on awkward.
The modern ones do have more cool mechanisms and gadgets, though. Also they include extra pieces for the small ones now, and more sets come with a brick tool. Those are all nice changes. But the sets themselves seem to be tuned for inflating part counts and looking nice on a box, not for play.
LEGO just has a much much larger catalog now than they did back then (200 sets vs 800 sets.) But the classic style sets are still there for you, if that's what you want.
The modern one reflects some... changes - the more contemporary window style, and the number of minifigs wearing ties in the firehouse has increased. I expect it reflects an assumption of a higher tax base in legoville. In all seriousness, the custom piece count is on full display, where the 90's set is dominated by reusable generic pieces.
Those outward-sloping windows in the 90's set were the bomb though, useful in so many cool applications - (star)ship bridges, towers, and the like. :D
Yes, the 1994 Flame Fighters is an outstanding set! My main dislike of the modern version is that the fire truck does not have a ladder (that would offer a lot of playability). The water gun just looks puny.
EDIT: still, even if I have a weakness for even older fire sets, I acknowledge that the modern lego fire stations are very good toys. My son has spend countless hours playing with the 2016 version [0], which is incredibly playable, and whose fire truck is the best.
A modern ~550-piece set, also from a line aimed at kids, not one of the adult-aimed models: 3 minifigs, fills 1/3 cubic foot at best because 450 of the pieces are little 1x1 and 1x2 plates or similar. Finished set's too small for even kid hands to get in and play. If it gets messed up more than a very tiny bit, you'll probably have to re-build from scratch, because the construction is... very CAD, I guess. All surfaces clad in smooth bricks if at all possible, making adding on awkward.
The modern ones do have more cool mechanisms and gadgets, though. Also they include extra pieces for the small ones now, and more sets come with a brick tool. Those are all nice changes. But the sets themselves seem to be tuned for inflating part counts and looking nice on a box, not for play.