I have an iPhone X, an iPhone 8, and a s8+. I switch back and forth fairly regularly, but was originally an iPhone user. It might feel a little limiting going from Android to iOS, but I find iOS to be the better platform overall. Especially if you use other Apple products.
Samsung products have been kinda iffy to me. I have the S7 Edge and absolutely hate it. I liked my Note 7's, but didn't really get to use them very long. The S8+ is a very nice phone, but I still feel the software is a little janky compared to my iPhones/HTC phones I've had.
If you decide to make the switch one thing to remember to save you some headache. Almost all app settings are managed through the main Settings app instead of inside the app itself.