Drove a E46 320i BMW for 17 years no major issues.
Got me a F30 330D BMW now. Don't care about expensive motorplans and useless warranties etc.
When people talk about high repair costs, its usually the agents that milk the warranty/motorplan company.
Why do they want to fix something when they can just replace the whole unit and make more profit.
Can a whole gearbox break to the point where it has to be replaced? Don't think so, but for agents its more profitable to put in a new one. The old one gets sold off and a good techie fix it for a fraction of the cost of a new one.
Best is to learn about cars and source independent repairers.