Super coffee nerd here.
I'm not a coffee-maker user, so not much help in this discussion. I do pour-over (V60 - $10), AeroPress ($35), or Italian moka pots (cost varies based on size), which technically is a coffee maker. The moka pot will give the strongest flavors of my three brew methods.
I'm still roasting green beans on my
Camp Chef stove. Just completed my 170th roast (Brazillian) earlier this week. 20 oz green gives me 16 oz roasted (Full City to Full City+ for nerds like me). I typically drink 2-3, 12-16 oz mugs a day of black coffee.
Robusta beans have double the caffeine of Arabica beans, but taste grassy and earthy. I avoid them at all cost. African and Indonesian Arabica beans can have a spice edge I don't care for. I prefer Central and South American Arabica beans because they match my preferences for chocolate and caramel flavors.
Something I learned recently is darker roasts can be brewed at a lower temp (175‐190°F) for a shorter time (1 to 1 1/2 minutes) to maximize their complexity. Medium roasts 195-200°F for 3-4 minutes. Light roasts 205-210°F for up to 8 minutes. I rarely roast lighter than medium (City to City+ level for the nerds).
Under extracted will taste sour. Over extracted will taste bitter. Grind and brew time and temp will impact extraction.
Grind size, brew temp, brew time, roast level, and method all can give a variety of flavors for the same roasted beans. Machines give one note because brew time and temp is constant, but can be impacted by grind size, roast level, and origin.
Strong coffee? A stove top moka pot will give the strongest that isn't actually espresso. It can be diluted in the cup with hot water if too strong. The AeroPress offers almost the same level of strength.
Time for my 3rd cup.
Ray