Easy choice for me as every other car I have owned has been at the very least fine.
1998 Vauxhall Vectra 1.6...
At the time I got this horrible piece of shit, I owned a 1989 Mercedes 190E 2.0 and it was fantastic. My first Mercedes and I knew it was the car for me.
However after a year of ownership I fancied something newer and my uncle had this vectra in that champagne colour. It was clean and tidy and he offered to swap it for the Mercedes.
I accepted and the deal was done however after a few days of ownership, I realised that it was a lemon. Noisy tensioner so it made that horrible whine they all seemed to make, it was underpowered, miserable to drive and uncomfortable
The thing that made it even more sour was that my uncle sold the Mercedes for quite a lot more than the vectra was worth so there was no going back.
I ran the vectra for about 6 months with plenty of trouble and misery and eventually had to get out
I sold it to my mother in law as for some bizarre reason, she quite liked it but alas, she had nothing but trouble with it and ended up spending a tonne of money keeping it on the road before finally the radiator exploded during the emissions test on the mot
It ended up getting scrapped
I used the money from the vectra sale to buy a 1987 Mercedes 190E 2.6 manual and never looked back. That is probably the best car I have ever owned