HLC the very best clinic? Even I wouldn't say that. Are they the best at €2.5/graft? Or better than Bicer? Personally, as an HLC patient, I absolutely say yes.
I did my research, too. I've seen most of the sub-par patient cases, and I agree a couple were not good. The others were fine, albeit needing a top up. But the vast majority were great. Natural hairlines and good density. I see no better option at their price point. To get better, you have to increase your budget to €3-5/graft.
You need at least 2 procedures. I agree 3500-4000 for your hairline and mid-scalp. You have a good budget, but it puts you out of range for the top clinics. If you can find another 3000-5000 Euro, your options open up. And this is just for your first procedure.... you'll need another $10k for your second.
Another strategy would be to go with someone like Dr. Turan or Dr. Gur, who are half the price. They could probably get you most of what you want. Probably get you everything you want over 3 procedures. And it would cost your $10k in total!
Just my opinion.