I think you can get an early model 27 from a Gun Broker auction and that seems like it would have more appeal to you, though it will probably cost you at least 50% more.
The 3" barrel was the only barrel length that we could call popular for carry other than open duty carry. The 3" was very much in demand for carry up until the model 19. For shooting, I would take the 6" or 6.5" any day. I think the 4" really became popular as a barrel length after the model 19 was introduced -- I mean as far as 357 is concerned. It was a popular length in the 38 K frame before that, but the N frame with a 4" barrel was bigger than people wanted to carry. I think the 3" was more popular. But as far as the Classics go, the 4" is the closest option and it has the Magna style grips that would have been favored for carry, as opposed to the Target grips that are on the 6.5" Classic.
Personally, I'm skeptical of the Magna grips. I've never shot a revolver with them but I don't expect them to handle well, especially with higher recoil. Also, it's a little irksome that Magna's were basically a cheapification of the classic grips that had the wood inlet for the half-moon on the grip frame. Basically, it took less skilled labor to leave the Magna's horns at the top of the grips instead of fitting the top of the grip into that half-moon.
The 6.5" Classic has the Coke Bottle target grips. I haven't tried them either but I've read that they don't fit many people's hands well.
The grips are easy to change, but S&W chose the grips they did because the proportions are well suited to the shorter and longer barrels respectively. If you have a grip preference, and no other way to choose the barrel length, pick it based on that.
