If you go see the white one (or is it dynamic grey?, either way best 2 colours) check the bucket seats here for tearing on the white fabric (its crap):
View attachment 27276
Also based on the mileage get it checked for being clocked (sadly more common than you'd think recently due to people swapping out the speedo etc).
As for ACC, I had it on my
280 and hated it, much happier with normal Cruise on the 300, but still has the front assist. The 300 does look like its only got normal cruise though as only has the normal cruise control stalk (ACC had a 3rd stalk on my
280).
Other options do look good (Seat Sound I had retro fitted).
As for the red one, not sure how the sun roof is on the hatch, I know the estate it can squeak but that's a bigger different unit. It has the standard seats that are very very good, just don't have the visual presence of the buckets.
Its a hard choice. The mileage is high on the 300, but the
290 maybe clocked. The
290 has some popular mods already done too (Splitter, spoiler cap and DSG paddles, although cheap ones). The
290 looks like an enthusiast has had it, so maybe of been treated really well or ragged, would be handy if you could find out who had it before. 300 Looks like it could of just been someone's rep car, so may also have had a hard life and treated as a work horse.
I'd go look at them both and see if there is anything that makes one of them a deal breaker or a deal winner. At the moment my nod would be to the 300, but only just and going off of face value.