title_body: Why does some coffee "hit me" harder than other coffee?
upvoted_answer: There are a number of concrete factors that will impact the stimulation you get from a cup of coffee, but it probably boils down to the amount of caffeine (and any other stimulants) that are in your cup that get extracted from the beans. Here's a few factors that affect the caffeine content of coffee, with links to other related questions on this site:
  
  
  Certain beans have more caffeine (themselves, per mass) than others, so there's more of it to get extracted into the cup;
  Certain roasts (e.g., lighter) have more caffeine than others (see also lowest-caffeine roast, or calculating caffeine content)
  Certain preparation methods have more caffeine (e.g., caffeine content of preparation methods)
  There are factors in strength and extraction -- e.g., more grounds and higher extraction will generally provide more caffeine.
  
  
  I'm lumping this all under "caffeine", but there are probably other stimulants in coffee besides caffeine (e.g., as suggested in this article and others). 
  
  And then there's the intangible factors in "stimulation", such as marketing, cafe atmosphere, and so forth, which might have some other kind of effect (like "conditioning" or other "mind games") that might help you feel like the coffee is even more stimulating than it would be otherwise. These veer off-topic too much to discuss further.