perugina 70% Chocolate is the best go to chocolate I can find. It's only like 2$ a bar at my local grocer and far FAR better than most other bars I've had. My wife and most of my friends agreed after we turned them on to it. I am unsure why this particular chocolate of theirs is so much better than everything they do but it's just perfect. It's pretty widely available too. I do not recommend other bars by them, and only this one.
If you want to drop some cash though, John Jelly - https://www.johnkellychocolates.com/ - makes some seriously amazing stuff. It's pricey but worth it. His stuff is more truffly and less like a bar, but damn it's good.
I should note I travel for work and my first day each week on my per diem I always go to a grocer and spend some on a fancy 5$, and I've yet to find one that compared to the Perugina. The one exception was when a friend at a grocer opened up a 12$ bar for me to try that was nuts like Vietnam. It was by far the best I've ever had, but also 12$ for a half size bar.