This has been heavily discussed in other threads and the gist of it is that it depends a bit upon where you live and the type of matches you will likely attend. Some matches, especially in the western states involve quite a bit of hiking and humping all of your gear around all day. That type of match will involve a slightly larger pack with room potentially for rain gear, tripod (inside or outside of pack), and extra water. An eberlestock G3 Lowdrag can do this as can any number of other good packs. The G3 has the scabbard.
Many other matches give you ample time to get back to your vehicle at points during the day and therefore do not require that you hump around so much all day long. Most of the matches that I shoot are of the latter variety and therefore I use a small pack with plenty of different pockets and molle for attaching things. It is rare anymore that I use anything more than my Maxpedition Sitka Gearslinger. It is small enough that it forces me to think about what I'm packing and therefore saves me from carrying around unnecessary weight.