This is gonna be harsh feeling but honest. First realize I'm a car Nut. I hate boring cars. I hate a life with boring cars. I also hate being broke, unable to advance in life, and seeing others do the same.

First, none of the requirements you stated exist together. Fun to drive demands compromise in two things 99% of always. Reliability, and mileage. Reliability demands the compromise of the same other two things. Yes, there Are exceptions. But they require a compromise too. And that compromise is that you're not going get one in good shape for under 15k.

I get it. You don't want to read any more. I'm not offering a solution. Well, I'm not offering an alternate reality that doesn't exist, no. But I can tell you what you should do if you don't want to work the next 4 years only to end it broke needing another car. I'll say first off if you insist on wanting an AMG still, good luck. You're screwed unless you make more money than you know what to do with and already own your own home. If you're reasonable read on.

1) Buy a reliable car that will enable you to buy a second fun car later. I hope you're focusing on bettering other areas of your life before owning two cars but that's none of my business. I'll just say a car will end up being your transportation to work or the only reason you work and the only thing you own. That's your call. If you want that, go test drive every Honda or Toyota at a local lot. Pick one you like and look on reddit to see what common issues they have. There's a sub for every car that exists.

2) buy a fun car but save half your budget to fix it when it breaks. That could look like finding a 9k Mazda, Acura etc with no rust. When the transmission or motor falls put a brand new or rebuilt one in it. Poof! You got basically a new car once you replace the boring suspension with nice adjustable coilovers.

3) buy a Really fun car with zero rust for dirt cheap and start replacing Everything with new and improved parts. This could look like getting any 2000-20010 car you love with ultra high miles but still runs decent. You find out how much every single moving part costs. You set the cost of the engine and transmission to the side and Don't Touch it. Go buy brakes. Go buy suspension. Buy the body kit you want. Get your taillights. Get some newer better seats. When the motor blows, replace it. Poof. Brand new old fun car that should last another 150k miles.

4) this is the one you should do. Find a compromise you can live with for now and appreciate the situation you're in. You have 15k. Dial that back. Don't spend it all. Research the hell out of Honda cars. Don't look at ones that sell for 12-20k and get forced to buy a shitty example. Look at ones that sell for 8-9k and buy an immaculate example. Pay it off and do it fast. Work your ass off and save every penny you can. Life is like a video game. You have to level up one or two levels at a time. Use that car to get yourself to a point where your budget isn't 15k but more. Then go get that AMG you want, and buy another reliable car at the same time so you don't end up back at square one.

So to answer your original question.... here's a good list of first cars.

Honda Civic, Accord, Fit/Jazz.

Toyota Corolla S Premium loaded. Take off the boring suspension and get food coilovers, light wheels, high quality tires.

Mazda C series crossovers, Mazda 6

Acura TSL with low miles

Here's a list of the worst first cars you can buy.

2012 and up Ford focus or fiesta/festiva whatever they're called I forget for those years.

Any high mileage Subaru (yes there's exceptions but it requires a lot of research and luck)

Anything made in Germany or either Korea.