I don't really have a recommendation, but you'd want to check the model number of the Oneplus 3T when searching:
There are also 64GB and 128GB versions of the phone available.
This 64GB looks like a good one, if you plan on buying from amazon.
I suggest not to rush and take more time to find more phones that are to you liking too!
You could grab a OnePlus 3 for $375, or a ZTE Axon 7 for $380. If you're willing to extend that budget by $28, you could get the OnePlus 3T, which definitely has enough improvements to justify the extra money. If you happen to have Amazon Prime and you're willing to deal with some ads on your lock screen, you could get an LG G6 for $400.
Those are all coming from official retailers, of course. If you're willing to go eBay, you could probably find most of the top phones from last year new-in-box for less than $400. I personally just bought a brand new LG V20 a couple weeks ago for $370.
But if you really want a phone that came out this year, these are all of your options between $275 and $400 and most of them either aren't very good or aren't available in the US. (Assuming you're from the US...if you're not, then you should probably stipulate which country.)
Considering that you won't buy the gold version, I'd take a look at this. That's the cheapest I can find it for, although I've never seen this website before, so I can't say for sure if the phone is used/if the website can be trusted. I would recommend that, if you really want the HTC 10, you should wait until the next HTC U Ocean/HTC 11 is announced. Hopefully that will lead to a price drop. Otherwise, I would go for a OnePlus 3 or3T, or even a Galaxy S7 which can be found on Amazon for $440 USD. Those will all be comparable to the HTC 10 in performance, if not better, and will be quite a bit easier to get a hold of. If you're going after the HTC 10 for sound quality, then check out the ZTE Axon 7, which goes for $400 USD.
I love the HTC 10, don't get me wrong, but it's awfully hard to find at that price point. For $600 CAD, you're better off going with one of the other phones listed.
My Oneplus 3 is the best phone that I've had so far. I highly recommend it. Also, there is this moto E plus on amazon for only $200
You can still find a OnePlus 3T from other retailers. For example Amazon has one here. I'd act fast though if I were you.
OP3 is $199 on Amazon: https://www.amazon.com/OnePlus-Graphite-Factory-Unlocked-Version/dp/B01H3V07EW
For your budget, it's the best option out there, reasons being: