I've had both the Logitech and Blackweb, and the Logitech has been much better. The Blackweb did get funky was when the battery was getting low. On my main PC, I use another wireless Logitech keyboard(mk345)...
...but I originally had it on the living room PC. For some reason it always had issues with connection, but when I moved it onto my main PC and just used the keyboard, since it was very comfortable, along with a wired mouse it works great. I'm guessing I was getting some sort of interference from either the Wi-Fi or bluetooth signal in the living room, and I don't run into that problem using it in the bedroom since I have ethernet cable via wall jack and use a wired Razer gamepad on that PC.
TLDR: Probably either weak battery strength or interference from other devices. The Logitech keyboards use 2.4GHz RF wireless connection, maybe my Nighthawk X6 router was messing with it.