I won't insult you by attempting to bash IDPA or PPC, since I don't (or even have the opportunity to) shoot them, except to say that they're probably great fun for the people who get involved, and I'm sure that they offer good experience for shooters.
I think I can comment on IPSC for you...
Organization:
IPSC Canada is the most active and largest action shooting organization in the country.
We are represented in every province except PEI.
In Ontario alone, there are over 300 matches a year. In little NS here, we have over 20.
IPSC has an established, polished set of rules with certification and structures for officials.
IPSC Canada offers an excellent training program for new shooters, that is very often copied (and always accepted by) other shooting disciplines.
IPSC Canada is one of the 5 biggest countries involved in IPSC (of which there is over 50) and many of the big players in the international organization hail from Canada.
Our Yearly Nationals is so popular, we keep expanding the time frame and working our people to the bone to get more shooters in.
If you want to put rounds downrange, you will definitely get a lot of shooting done with IPSC.
The Sport:
We started with defensive techniques, but found that if we wanted real objective rules and a standardized playing ground for all our competitors, we had to move away from it. Some features are still implied, but it's really about the competition level now. That said, many of the concepts of defensive pistol shooting (don't stay still, trigger control, sight alignment) are accentuated. Nobody in Law Enforcement has ever said that shooting IPSC didn't help them.
In Canada, we offer 4 different divisions of competition for your preference of handgun. Revolver, Standard (single actions with no comps, ports or optics), Production - box stock (mostly) guns and Open - whatever you want to do to it is up to you.
IPSC Stages are never repeated - anywhere. That means you'll be faced with a new shooting challenge at every match you go to. No muscle memory games and you won't get bored. You may be shooting with either hand, both hands, off balance, running, 50 yard shots, etc.
IPSC offers "Long Courses" which are 18-32 round challenges that are sure to get your adrenaline pumping.
The Guns:
The only shooters that win IPSC matches have flawlessly working guns that fire thousands of rounds. You can't win with a gun that jams occasionally and you can't get good if you don't practice, so be sure that the guns you see at an IPSC match can take a beating far worse than any LE/ Military selection process.
The People:
Since this sport can be so competitive, we attract "A" type personalities who get very passionate about the sport. The occasional one makes an ass of himself at a match, thinking only of his placement.
He's the exception, and the same joker you'll find at every sport that has a competitive level. The majority of our people are friendly, helpful and great people to hang around with. I've been all over this country shooting and there's no place I wouldn't go back to. I've made friends all over Canada and in many other countries. I wouldn't have got the chance if it wasn't for IPSC.
The Matches
We try very hard to build elaborate stages. We train our match directors and officials that they need to put out painted walls to shoot around, nice props and entertaining ideas. We strive for it, but understand that at some smaller matches, the budget isn't there, so we make due, but the challenge is just the same.
Short Courses are 1-9 rounds, quick shoots whereby you get your gun and shoot. The sneaky thing about these is that you get the impression you have to be fast and let accuracy suffer, but in fact - accuracy is more important.
Medium Courses involve some basic movement as you shoot 10-16 rounds.
Long Courses involve lots of movement and lots of mag changes (in Canada) as you shoot up to 32 rounds.
You'll find all of these courses at each match.
I suggest you contact Mark at IPSC BC and come on out to one of our matches, it won't take you long to get hooked.
Sean Hansen, Regional Director, IPSC Canada.