GG, this is a personal thing, but after living with my 35i M for 18 months I have settled for this:
-city driving: auto/comfort - gives "nice" shifts and I don't have to think
-In Sport gears will hang in too long - annoying.
-open road: man/sport - gives me perfect control over gear and shifting.
-I save 0.5-1 sec when overtaking by pre-select gear for 3500-4000 rpm
-since I am used to stick, I prefer shiftstick prior to paddles.