Two entirely separate questions here.
I personally prefer the appearance of the K12 (at least my 3 door Sport+, SR look alike
) to the K11. It's really a Marmite thing, I like 'quirky' which probably explains why my last two 'main' cars have been Saabs
. However on the reliability side of the question, the K11 appears to win hands down, OTHER than the inherent rust problems that let them down badly. Some variants of the K12 are far to complicated for the price that they were originally sold for, so quality suffered.
I bought my K12, as a one owner car with low mileage (63K miles) and a full service history, for £1100, knowing that it needed a new rear wheel bearing, was a due service and needed a couple of tyres. 'Lucas' wheel bearings were £14 a piece so I changed both as a matter of course, gave the car a full service. Very pleased with the car and it's specification level.
I did however have a clutch driven plate support spring failure, which meant I had to put a new clutch in it, (just over £70 for a full 3 piece 'LUK' clutch kit), but put that down to the previous lady owner probably riding the clutch at stops during her ownership, which is something that can happen with any car ................