I just sold my 3 months old iPhone 7,now using my spare iPhone SE while deciding whether I should buy Galaxy S8+ , or wait for next iPhone and Note 8 or just buy an iPhone 7 Plus.
Original plan was to replace my iPhone 7 with 7 Plus.
But seeing Galaxy S8+ ,it's hard to justify buying old,outdated,un-necessary huge design of iPhone 7 Plus at this point.
and iPhone 8 rumours and leaks so far are pointing to an un-attractive design with crazy price tag.
As someone who owns both a S8 and iPhone SE, I believe I can offer really great advice. The iPhone SE is a great device to use, especially when waiting for the late 2017 smartphones. You know that you have iOS 11, Apple Pay, frequent updates, Wi-Fi calling, great battery life, a 4k camera, a fast processor, sufficient RAM, frequent app updates, Touch ID, and a premium build smartphone. You can use that device to your liking up until the next phones. Waiting is perfectly fine because the S8+ pricing will only drop, not go up.
As for the S8, it's the best phone I have ever owned. The screen is drop dead gorgeous and not just a mere 640p display. I love the camera, biometric features, software features, dual edge screens, USB-Type C quick charge, phone design, amongst the other features. Battery life wise, the S8+ is incredible from my dad's usage on his. Bluetooth 5.0 will do wonders along with the Gigabit capable LTE-A radio. I believe you will enjoy the S8+ as well.
However, the Note 8 and iPhone X will be relative unknowns right now because of various rumors. Will the Note 8 get a 4k screen, 6gb RAM, and a new processor? Will the iPhone X have a rear fingerprint sensor (same with the Note 8 in question) or a front-facing one? Could there be hardware defects with both phones? What will the pricing be? Do I need the S-Pen? Would I need the additional hardware on the Note 8 vs the S8+? Will the iPhone X have iOS 11 features exclusive to the device? These are the questions that will be answered as time goes on.
My recommendation is to wait because you save $ and your current SE is a great stopgap phone. I know that once my S8 goes back to my carrier, my loan plan will be cancelled out. I will go to using an iPhone SE for awhile before committing to a Note 8 or iPhone X for 2-3 years.