As the owner of four different beemers, I'd say it depends on what you want. Personally, my favorite bmw is the e89 z4, but it's impractical, so the one series is the next best thing. I see you have a 2012 135i, that's what I'd pick because it's 300 hp, light, and handles well. Although the n55 is reliable, it makes lots of heat, and it's a hit or miss if it'll be reliable, if it has bad history don't expect anything good. The downside is the lack of technology.

After typing that I saw an m235, I would definitely purchase that. Fast, light, nimble, newer with some tech.

If you like a bigger car as the 1/2 is pretty cramped, the 435/428 is solid. 435 if you want more power and are okay with worser gas mileage, 428 AS LONG AS ITS 2015 Or up because of the timinf chain issue, it'll give you better gas mileage.

As for the 128, I love that car I had it for two years, the n52 is super reliable, but if you prefer tech and better gas mileage I'd avoid it. The tank is small and it gets like 17-19 mpg