This has probably been talked about before on this forum, but here are my opinions about the different ways coffee can be made. Chime in if you like.
"Good coffee" is in the eye of the beholder. It depends on what your preferences are. I'd caution you to give each method a fair shot before dismissing it out of hand. Each one exists because someone somewhere thought it was a good idea that produces at least serviceable coffee.
Non-comprehensive list follows: if you know anything about one I missed, feel free to add it:
Application | Grind | Method | Result if done properly |
Espresso | Very fine, almost sandlike | You need as much surface area as possible because steam is in contact with the coffee for only about 20-30 seconds. | Thick, syrupy, sour, intense shot-sized cup of coffee essence. I find it hard to pick up on the flavor notes that other people can |
French Press | Very coarse | not quite boiling water in contact with the coffee for 3-4 minutes. It's kind of like steeping tea | rich, rounded, full-flavored, and yes, some sludge in the bottom of the cup |
Drip | Somewhere in the middle | Water contacts the coffee once, extracts what it can, and drips out the bottom of the basket | Brighter, harsher, somewhat bitter because the water gets a little too hot in most automatic coffeemakers |
Urn-style Percolator | Whatever | The water boils up and is splooshed over the coffee over and over again so it's going to get every last little bit of flavor, good or bad, out of the coffee | Bitter, overextracted, tired-tasting, but it does have caffeine |
Pods/Keurigs/etc | who knows | the pod machines do what they want and give you what they want | if you like what they provide and can afford it go for it |
I'm not sure what kind of stove-top percolator Tiogyr is referring to, but I'd love to hear more.
As to beans: the market tends to favor dark roasted coffee (French Roast) because there's a perception that strong-tasting coffee is stronger/cooler/better. Coffee providers can provide that by taking cheap beans and roasting them dark, baby, dark, resulting in homogeneous-tasting blah coffee.
If you roast on the lighter side, two things happen: 1) The flavor notes stick around and you can start to taste the varietal flavors in the beans themselves rather than dark char 2) Less caffeine is burned off so you get an actually-stronger cup of coffee
As has been mentioned earlier, adding a bit of salt to cheaper coffee being brewed less carefully can make it more drinkable... to my palate it smooths out the flavors a bit, but I'll defer to Tiogyr on the chemistry.