Very interesting Toulous. There's a lot to address here.
Halogen Headlights.
I was surprised to hear you say that you prefer these over your old headlights. The key question here is, were they halogen projectors or reflectors? If halogen projectors, those are pretty good headlights. Halogens tend to have better CRI with 100 while LEDs have around 80 CRI, depending on the quality of the LED. High quality LEDs will of course be more expensive and there's no way to tell if your headlights have quality ones or they were cheaped out on.
LED Headlight.
I've driven in cars with LED headlights and didn't find comfort or visibility much of an issue. Only thing I can tell is the color difference. But it also may be that the issue flew over my head.
Headlight aim.
Car headlight aim generally does not ever need to be touched. The only time you need to reaim it is if you replaced the headlight unit. But the general rule is this, measure a distance of 25ft from the headlights and a line on the wall to the height of the headlight. The cutoff line needs to be two inches under the center of the headlight. As long as the beam continues to fall, then you won't blind others. If your aim is lower or higher, you won't get the full benefits of distance because the beam is dropping down too soon. I would get the dealership to properly aim it. Although, headlight aiming can be quite technical and the technician needs to be competent, otherwise they are just committing the same problems as a regular Joe would.
Brightness
Halogen projectors arn't going to be as bright as LEDs because with LEDs you have a wide range of parameters you can set. With halogens, you are stuck with a single preset of lumen output. That said, halogen's performance is very good. Brighter isn't better. Too much detail can be a bad thing for driving comfort.
Current Situation with headlights
It seems like the manufacturers are trying to phase out everything halogens. But I think that's a bad idea. As car designs become more embolden and striking, the manufacturers will keep have having to have a shock factor buiilt into the design, and there's no better way to do that than with high contrasting headlights. That's why in my opinion older cars were better in this regard.
This trend isn't going to stop.
Headlight restoration
Another consideration is that the front covers on the headlights will fade over time due to UV. This reduces the light output and causes glare. This isn't a problem on new cars but it's something to consider with older cars. Once the cover becomes yellow, it needs a lot of polishing to remove the damages to get it back to 80% performance.
What I would do.
I'd get an older car that's in good condition. You don't want to get something too old because then it'll have mechanical problems. Take this with a grain of salt though because I don't know your exact situation to make an accurate recommendation.