Personally, I like ZTE.
Yes, you get the standard bloatware.
But the cost is good, the quality is good, and the UI is simple and effiicient.
I find that when I must deal with someone else's device (Samsung, I am frowning at you) I wish that I was dealing with a ZTE.
As far as Wi-Fi calling goes, it is up to your carrier as to how/if it works.
To get around rhis, just use a Wi-Fi calling app.
There are many of them available.
Personally, I use Dingtone.
I get a free phone number that anyone can call or text to, and it acts as a separate line for my device.
You can link up to 5 devices onto one number, and even devices like computers and tablets.
There is even one Wi-Fi calling app that I have found that does not assign you a specific number, but gives you a different one for each call.
That is an outgoing calls only app.
The only options that I have tried are the free ones, and out of those I have to say that Dingtone has treated me very well during the 3+ years that I have been using it.
There are not too many hoops to jump through, and the calls are generally clear and the app works even on the crappiest of smartphone devices.
When getting devices from the supermarket, keep in mind what carrier you have, or want to use.
Getting a device that works on a big company's (AT&T, Verizon) system is important if you want reliable service, so stay away from small, local, or regional carriers that use devices that may not be compatible in all areas.
Most of these type carriers are renting time on a large carrier's towers anyway, and by using a renter's time on such towers your service may not be up to par with the customers of the tower owner.