A watch that keeps good time is the primary function.
Secondly, I like the watch to have a good look and feel. The cost is irrelevant and the subtle details do not matter that much to me. That being said, I really enjoy trying to make a watch "closer" to the real thing. It's not so I can pass it off as a gen, but more of a challenge to see if it can be built with available parts.
The reps that I have collected this short 9 months (or built) feel really good and sturdy and were a fraction of the cost of the real thing. I've had opportunities to evaluate the gen's, and IMO there is no need for their extremely high cost. It just doesn't make sense to me at all.
At the end of the day, I love watches, and reps are what I choose to afford. I could save up and buy the real thing, but I'd have a hard time justifying it to myself.