Reliability wise Jetta vs A4 is 6 of one, half dozen of the other. Either one should get you 200k+ without any major failures. And yeah they actually are pretty easy to work one once you get used to the way they’re designed. Parts can be had for less than an arm and a leg (maybe just an arm) if you know where to look.
Good cars, a pleasure to drive, just know that you will need to work on it from time to time.
If I could go back in time though, I would have gone A4 instead of Jetta. Audi quattro >>>>>>>>> Jetta FWD.