Whether or not it's a waste depends on factors like whether you can afford to run a car and whether you actually need one or could cycle/use public transport.
If you can afford a new car, I think if it was me, I'd get one, especially as it sounds like you're the type of person who gets a modest car and keeps it long term so probably the cheapest way to run a car, you're not driving something newer/bigger/more expensive to run than you need and you're not always chopping and changing.
If you get it fixed, you could be looking at £1k+ when labour is included, and you're unlikely to make that back in resale if you sell it shortly afterwards. If you kept it for a year or two, you might be lucky and avoid further big bills, but if not , that money would probably have been wasted. Your mechanic might actually be interested in buying the car off you, because they often fix up and repair cars for sale, the garage we use does that, as does a family member who's a mechanic.
As for your replacement car, it's almost like you were me 18 months ago. For most of the last 20 years I was a company car driver but my last car came up for renewal fairly early in the pandemic but far enough in for me to know that due to the WFH revolution, me having a company car was going to become a bit of a luxury (we have to pay quite a lot towards the cost for personal use) as I've likely never need to commute every day or visit clients as often as I did in the past.
So I bought a cheap old Mini on a bit of a whim, drove it for a few months, then it spectacularly failed its MOT, so I decided that my 'bangernomics' experiment had failed and that if I wanted to run a car while spending as little as possible, the best thing to do would be to get a decent small petrol car with the plan to keep it long term, so that's what I did.
Mine is a Skoda Citigo that I paid just over £8k for from a car supermarket (very easy, no haggling and the price was very fair - with hindsight, I was very lucky with the price as prices seem to have risen since then). The same place is now selling 19 plate Citigos for over £1k more than what I paid, despite these cars now being nearly 2 years older than when I bought mine.
Out of your list, I'd go for a Polo or a Corsa (or what about a Honda Jazz or Seat Ibiza, or if you're only ever doing short journeys an even smaller car, if you're not moving lots of big things or teens?) and if you get one that is older than about March 2017 (check this) then you'll likely get one with £30 per year or less road tax, so if you're going to keep your car for a long time, a decent saving over a slightly newer car. I was going to do this, but then I saw a 19 plate for not much more than what the ones that were a couple of years older were going for.