I suspect you're talking about 2 different issues here. One is low connectivity, and the other one is simply not getting the WiFi to turn on at all.
I am experiencing the latter, and I have a HTC One X Plus, which came after the confirmed HTC One hardware problem they claimed had been solved in production.
I cannot get it to stop trying to turn the WiFi on at all, and it's draining my battery incredibly fast.
I will send it back to them and hopefully they'll get the issue fixed.
Anyway, for me the HTC brand is not looking so good anymore. It's clear enugh they couldn't fix a well known problem even after releasing another product entirely.
Next time that I'm researching a device, I'll simply look at the technical features and ignore all the praising bullshit. What I will do in return is simply google "blabla_device_name PROBLEMS" and see what comes up. Lesson learned!