Hello!
It all depends on what you're looking for! If you want the best bang for your buck, then I believe the Honor 8 Pro is your best bet.
If you're looking for a flagship device that will also come at a good deal and one that is a little on the bigger side (that was a weird sentence lool), then the G6 is a good option for you. It's one of the best flagships out there but also one of the most economical, IMO.
OnePlus 5 is said to be known for its great camera shots, and ratings so far have been good. If you're into taking photos and having a unique user experience, I'd recommend the OP5.
It's definitely a tough choice, as all three would make excellent daily drivers. If I was in your position, I'd take the 8 Pro, as I have the Honor 8 and love it! EMUI (the Android launcher Honor uses) also gives you a unique and very customizable user experience. If you like changing things up often, EMUI's Theme Editor could help!
Let us know what you decide!