Must be compact or full size.
Must be in a commonly available caliber. (lets be real - 9mm is hands down the obvious choice here, its the most popular, affordable and available defensive round. Get out of here with that out dated .40! - more of my opinionatedness)
Must be a gun that is readily available.
Must be a gun that is purchased new.
Must be affordable.
Must be striker fired. ( I know this will get a bunch of backlash. But when teaching a new shooter how to be proficient in self defense, accuracy, maintenance of the weapon, ect... I feel that a striker fired firearm is going to serve the general public better than a DA/SA and better than a SAO with a safety to fight with and train on.)
Basically, I think must can generally agree those will be the criteria, like it or not.
Still, I explain to new shooters:
Full size cause you have to shoot a lot comfortably to improve.
Available locally is often key to the new shooter.
New is often important to them.
Affordable varies, but many want to go bottom shelf. I guess their families safety is often bottom shelf starting out.
Striker fired I agree, but don't like it. Still lots of fantastic plastic striker gun are the rage today.
Last, I'll add must have thumb safety option. Most newbs and many experienced shooters don't like to administratively handle a gun without a safety.
The Canik is a fine pistol I'm sure. I have a few questions that apply to newbs and maybe experienced alike:
What is general trainer knowledge of these?
Am I likely to be offended whe Joe trainer says don't buy a Turkish dud and put it in your night stand?(these statements should often be viewed as ignorance unless personal experience can be explained.)
Can I find a local gunsmith with Canik experience?
What are my sight options?
Are spare parts available? From where?
How is warranty service?
Who makes holsters? Blue gun available?
For these questions, Ruger options look pretty good. They also feel great in the hand.
Also, I'm not sure if the days of the $350 XD9 are over, but that is another great option.