Ditto on the rattles - I had a 318 years ago from new with a rattle on the drivers B pillar - drove me to distraction - according to the BMW specialist that that the dealer eventually wheeled in it was due to the over use of wash / wax shampoo hardening the door seals, seals replaced, rattle gone - I’ve always lubricated door seals with Gummi Pflege since.
GTI has been great, I personally think the build quality is better than the BMW / Mercedes / Land Rover Discoveries I’ve had over the past 20 years.
However, my mates wife has a M135i and it is a lovely car, feels rock solid, I don’t think you will be disappointed (and it hasn’t got a sunroof😄)
I’ve always had an itch for a GTI from being 15 when they were first launched and now I’m fortunate enough to have one. Working from home with no kids and associated crap to ferry around anymore it’s just used for fun, which is great.