I suspect such a map doesn't exist, but if you want optimal Internet connection, what you're looking for is:
a) in a metro area that has a major internet exchange. Hurricane Electric's list of pops is a decent start: http://he.net/ip_transit.html Some of those locations are more well connected than others though. In the US, prime exchanges are really LA, SF/SJ, Seattle, Reston, New York, Miami, Dallas, Chicago. If you settle near a lesser exchange like say Denver, you'll probably have good connectivity to many networks, but many services don't have a datacenter in Denver. Also, some companies are trying to put their big datacenters farther north to save on cooling and energy costs, so bias north if possible; however, if you want excellent connectivity to South America, much of that goes through Miami.
If you're in Canada, Vancouver or Toronto are your best bets. In South America, Sao Paulo or Bogota (but note, connectivity is sparse between countries, it historically all went through Miami, but that's changed a bit). In Europe, Amsterdam, London or Frankfurt? In Asia, Singapore or Taipei. In Africa, Johanesburg. In AU/NZ, reportedly it kind of all sucks, but Melbourne/Syndey/Auckland are okish.
b) not on DSL; usually it's run with settings that guarantee you 20 ms ping to the first hop. Be careful because some of the DSL providers imply fiber to the home, but really mean fiber to the DSLAM (or whatever it's called today).
c) fiber is better than cable, but cable is ok as long as the company isn't incompetent. Comcast is much maligned, but their network is actually pretty good; local areas could be mismanaged though.
d) you need to actually put potential addresses into the sign up for service pages. Put the one you're looking at, as well as the neighbors; if you get prompts like 'you've already got service, would you like to manage it', that's a good sign that they probably actually service the address. Listed available speeds to addresses that are current customers are more likely to be accurate as well. If there's a public utility fiber, check their fiber map, but don't expect to hear back from them with firm availability or not in time to make a decision on your prospective living arrangement.