I'm a little slow in catching up on my reading, so I just found this and thought it interesting.
IDPA does a survey at their Nationals (not the indoor held at S&W, but their "National" match). The results of which are very interesting. It took me many years to learn to quit trying to re-invent the wheel just for the sake of doing it. After digesting these numbers I may make some changes in my reloading.
This match was held in Septmeber in NC and had 314 pistol shooters and 30 revolver shooters. Here are the top numbers in some of the more interesting categories. Excuse typos and I might be off by a couple. Not everyone responded to the survey so things might be off a little.
Pistols: Glock - 108, S&W - 76, Springfield Armory -25
Revolvers: S&W - 26, Ruger - 1
Holsters: Comp-Tac - 107, Blade-Tech - 87
Ammo: Handloads - 185, Atlanta Arms - 32, Federal - 24
Powder: TiteGroup - 61, Clays - 22, N320 - 20
Bullets: Montana Gold - 67, Berry's - 27, Precision Delta - 26
(Jacketed - 108, Plated - 43)
Primers: Federal -79, Winchester - 46, CCI - 31
Reloading Press: Dillion - 189, LnL AP - 5
(Note: More people indicated a press than indicated they used handloads. I wonder if some competitors use factory ammo for competition but reload for practice or other purposes?)
There were more categories but these were the most revealing. So if you're just starting out in competitive shooting or reloading and you want to know "which should I use?" well here's an indication what the crowd is doing. Not necessisarily the "best", but it shows the trend.