First, regarding the two things you mention it lacking - wireless charging and a decent water resistance rating:
Is wireless charging a 'must have' feature for you? I had it on my N7 and N6, but didn't use it much given the heat generated and the adverse effect that heat has on long term battery life. To me, the only way it could be needed would be if the charge port connector were damaged to the point of being non-functional. With the old micro-USB ports, that was a realistic concern given the directional nature of the connector and an error in lining it up leading to loosening the port. With USB-C, it shouldn't be.
As to water resistance, I'd say the Pixel is "decent," just not exceptional. You don't need to worry about it being caught in rain or, as evidenced in many a video test, after quick retrieval from a drop in a puddle. It's not "great" like those with IP67/8, but unless you spend a great deal of time around large bodies of water, it should be sufficient. That said, better is always better, but the pertinent question is to whether what it has is enough to allay concerns.
Beyond that, I love the new competition coming out. I don't think they make any compelling case to switch away from my Pixel, but they will incent Google (hopefully) to go further with innovation than they might if the wireless handset market weren't such a competitive-leapfrog landscape.
I've had my Pixel XL now for.... actually, 6 months to the day. In that time I've had 0 trouble, and have not noticed any deterioration in performance or battery life whatsoever. I can't say that for any other smartphone I've ever owned, including the Nexus line. There is no area where I find it to be insufficient, and it excels at nearly everything. My only gripe is regarding the lack of front-firing stereo speakers (as that's what I had been used to on the Nexus 6 from which I'd upgraded), but in truth the single speaker is still very good.
If you're looking to upgrade now, the Pixel is absolutely worth consideration. Bear in mind that while it's a '17 phone, in 2 years it'll be upgrading to Android "P" whereas the latest round of flagship competition will likely be stalled at "O." Also, you mention possibly switching carriers. With Pixels, you're free to move between carriers without having to change handsets, which is a nice potential boon.
All that aside, if you're not in a rush, we're about another 6 months out from the Pixel 2 which will likely be a substantial upgrade. If I had resisted upgrading from my N6 (which still worked great) to this point, I'd give serious thought to holding off a little longer.