Of the three guns listed, I'd say KJW hands down.
First, I should mention, that although airsoftmegastore states they ship to Canada, they ONLY ship stuff in their Canada section. Those pistols are shooting too low to be classified as an "unregulated firearm", and are instead "replica firearms", which are illegal to import.
It's against forum rules to really discuss the acquisition of airsoft guns outside the Age Verified area, but I figured I'd give you a warning about importing.
Anyway, KJW M9s are quite common, and are a good mid-range gun. They are a Tokyo Marui clone, so you'll have lots of aftermarket parts. (btw, when you're looking for parts, you'll find most sites list them as Tokyo Marui (TM) parts, and not KJW parts).
WEs seem to be less popular (and a lot of people still have a bad taste in their mouth from the earlier gens that they put out), so I don't know a whole lot about their current quality.
I believe HFC is also a TM clone, but I haven't heard people talking about it, so I have no idea where the quality is on their guns. I don't hear people praising them, or going out of their way to recommend HFC, though.
Another that you could take a look at are KWA (on par, or higher than KJW, depending on who you ask), which has a functioning decocker (so when you put it into safety with the hammer cocked, it will decock it, just like the real one). KWA and KSC are the same brand, if I'm not mistaken. If you buy it in Canada, it'll be known as KWA. Note that KWA is not TM compatible.
Increasing or decreasing the velocity of a gas gun isn't as simple as just swapping a spring in an electric gun, so you might want to look into getting a pistol that already shoots in the range you're looking for. most pistols shoot well below 350FPS, which is the nearly universal limit for indoor CQB fields in Canada, so 310-340 FPS won't need to be lowered at all for playing.
If you're fine with spending lots of money, go with a TM M9, and pop it into a metal frame. If you don't want to do that, go with a KWA for its realism. If you want to go with just a good mid range gun, go with the KJW.
I read a review on TM's new M9A1 (all airsoft guns in Japan are plastic, so the TM M9 series guns, of all generations, are plastic), and it finished with: "So in summary - do you like the M9? Do you skirmish? Do you use a pistol? If yes, then buy the TM M9A1 and you will not regret it. If you don't skirmish, pick yourself up a KWA M9 as you'll not need to worry about its shortcomings, and can instead enjoy the enhanced feel of the metal body."