I currently own an AT&T iPhone 6s Plus and an AT&T iPhone 7 Plus. At my home I usually get two or three bars on each device. I have run more than a dozen LTE speed tests with the devices side-by-side at the same time while connected to the same server. Every single time the iPhone 6s Plus has a better ping, faster download speed, and faster upload speed. Furthermore, the iPhone 7's download is much more erratic and is always the slowest for the first few seconds (most critical time since most downloads are small). Conversely the iPhone 6s Plus always starts out at its fastest, is more consistent, and still ends up faster than the iPhone 7 once the test is done.
Unfortunately, it makes sense for Apple to deliberately slow down the Qualcomm version of the iPhone 7 so people don't get pissed off that they got a substandard device with the Intel chip. My hope is that Intel will release a better driver in upcoming updates so that it will perform at least as good as the iPhone 6. If they don't in the next month or two, I will be seeking to exchange my AT&T (Intel) version for the Qualcomm version.