I mentioned the Lexus IS since I've read it's an exceptionally good car. Being a Toyota quality is excellent and maintenance is cheaper than other high end cars. I think it's probably also undervalued in the used car market compared to say BMW or Mercedes which have better name recognition in SA. Feel free to correct me if you think I'm wrong.You mentioned the Lexus IS as an alternative, so I assume you are looking at compact executive sedans?
I would throw in the VW Passat 1.8T, Honda Accord 2.4 and the Volvo S60 (one of the 5 cylinder models) to also consider. The A4 of that generation (the B8) would have the oil consumption issues in that 1.8T iteration (note that the Passat motor is slightly different). The C-Class is also worth checking out, but may end up being less reliable than the E90 320i. My personal choice would be the Honda 2.4 Accord with a manual box.
I appreciate that you came up with other possible cars, but I've decided to focus on BMW 3-series and Lexus IS. Like MR_Y said above "researching and vetting a car takes significant time and effort and I need to limit the search tree in some way or else I'll spend 80 hours a week on car forums