5 speeds rule in my opinion
I have 4 Autos and 2 - 5 speeds.
In my youth I was a bike street racer, had a 10 second Suzuki, almost killed myself a half dozen times on the street. Many weeks in critical condition, etc....
I have since moved onto cars and midlife crisis.
The one 5 speed is quick enough to out drag a 330i and just edged a 275hp camaro to 100mph......looses about few car lengths to a C5 to about 100mph. I have never had so much fun with a car. Have driven many performance cars, BMWs, vettes, had a 428 supercobrajet mustang, my wife has a 99 328 (boring), ....but this 5 speed is the love of my life.
The other 5 speed is a stocker and is very boring and to the point of frustration on the road that I have to try so hard to beat cars that I meet up with. That's the downfall of a stock or not so modified 5 speed.
A stock auto by comparison could be arguably much more fun.
With a stock or reasonably modified auto you can do easy burnouts from a stop light, which is fun, plus you can beat most cars while eating a ham sandwich. But once you get to higher horse power, you will probably find that you will have control problems in certain situations on the street, especially kicking down to 2nd around turns at high speed, etc. The lentech would be a big improvement in this regard because of the driver switchability in all gears.
The auto also has a lot of utility in playing with cars in 3rd gear (assume stock gearing) going to around 100mph. I have beaten supposedly formidable opponents (227 hp subarus and many others) using the SC stock auto in 3rd gear in that 70 to 110 mph range.
The only downside I see in the auto is the fact that you would be reving higher in 3rd for a greater percentage of the time as compared with the 5 speed in 4th. The 5 speed in 4th can do approximately the same damage on the street....but I would give the edge to the auto in that range.
Bottom line is many people here are into dragging....many not be into street racing like I am. I get my kicks racing 330is on back road and things like that. I also like driving superbikes off the road. That's the kind of fun you can have with even a reasonably modified 5 speed.