Welcome to the forums! My mom and brother had the S4 and loved them! Well, my brother hates techy stuff so he tolerated it, but my mom loved it! Haha.
With regards to the OnePlus 5, I think it's a great buy! A bit more expensive than its prior iterations, but it's still a great bang for your buck. Any particular reason why you are steering clear of Samsung devices? The S8 is really good too, however it is quite the pretty penny nowadays!