Having only ever owned classics or hot hatches, the first thing i noticed about my mate's BMW 3 series is the price of parts and especially consumables like tyres. Generally speaking bigger wheels = pricier tyres. A 2011 - 2019 model as youve chosen there would be my pick for 'most reliable', but i havent heard much good or bad things about the 1.6 in your model there. I would watch out with that one though as the black wheels on that model will not have been standard so its possible that the car has been ragged a bit (common with lower spec 1 series cars as often owned by chavs - no offense to you!!) I'm also surprised at how much that one costs - personally I'd look for maybe a 2011-2019 model with possibly more miles but more service history (the one you sent has none as far as i could see). BMWs are lovely cars but are pricey when they go wrong especially modern ones unfortunately. Keep looking and as long as you can comfortably afford it with a grand to spare in case anything goes wrong I'd be happy buying one!!
If you're looking for classy cars for the same price or less which are more reliable and cheaper to run I'd look at...
Audi A3 S Line (1.4 TSI or TDI both are good engines)
Mk7 VW Golf
Peugeot 208 GTI