IMO its a pretty easy decision (for me it was)
If its a daily driver that will be anywhere near town centres or London for any period of time Auto wins all of the time, nothing beats sitting in traffic and not having to clutch or change gear. SMG might be a second best but I can't comment as ive not drove one of those.
For a pure sports car fun car that is to be used more on A/B Roads then manual all the way nothing beats running through the gears on a twisty section. (Auto can do this as well but this is where 15 years of manual driving takes over my mind.)
Now to blur the lines.
Modern autos (none torque converter) seem to have come on a long way like the DSG* /PTK. I had a session with a Mercedes driver in an AMG C63 and that was an auto. When he put it in manual mode on the track at brook lands it went like a scalded cat the level of engine braking coming up to the corners was insane double blip on the paddle and your in the gear for the corner there is no way a manual could compare.
Ok this is like comparing a Duran fruit to a Mango (200is HP E85 slush box vs 400 ish HP C63 AMG supertonic with a racing instructor behind the wheel)
*I hate DSG farts they just sound obnoxious when driving around town. Saw an RS4 yesterday was driving about 30mph in what sounded like 1st gear at full throttle then you just hear buurrrrrr pffhhtttt and you think what a c*****
I don't know what is worse DSG farts or the old turbo boys of the late 90s early 2000s with their to air dump valves that sneeze every gear change.