Basically, the shorter the jump range, the more systems you'll hit, and the more scan data you'll get (plus you'll find more interesting stuff like ELWs and strange stars). BUT...it will take you massively longer to get anywhere, so it will be harder for you to get to your destination, and space madness will set in sooner. I've made my couple of runs with around a 25ly jump range, and its a bit painful after a while (I was doing pretty well on my second trip out with my Clipper, but then had a case of bad judgement and sudden distraction cost me the ship and over 1000 systems worth of data....and I'd only gone about 9kly out, although I'd gone 2kly "up" through the galactic plane, bounced around a hell of a lot, and even had done some backtracking when I found interesting looking systems).