Really depends on what you want from a phone. I do mobile development for my day job so I switch between iOS and Android as my daily driver, and each has its strengths and weaknesses.
Android is far more customizable; you can do all kinds of things to really make a handset 'yours'. Custom launchers and lock screens, using things like Tasker to make your phone stay unlocked at home or put you in Do Not Disturb mode when face-down on the table or when attached to a car mount, etc. On the other hand, actually doing that customization can be a headache, and Android's Bluetooth functionality—especially Bluetooth Low Energy—is wildly inconsistent, and not nearly as reliable as iOS. There's also the fact that Android's going the same direction as iOS and getting rid of the headphone jack in favor of eliminating ingress avenues (for better weatherproofing).
iOS is far more locked down—it's very hard to customize in any meaningful way, so if there's a bit of behavior you don't like you are really sort of stuck with it—but it's also much harder to break an iOS device as a result. And if you have anything that uses Bluetooth wireless connectivity, generally the experience will be a lot better on iOS. And of course, no headphone jacks any longer; you'll need an adapter if you don't use wireless headphones.
If you do go with Android, I highly recommend a Pixel device; they're a little pricier, but really the most solid Android experience I've found, especially for the first generation Pixels. (The Pixel 2 has a few quirks, and the lack of headphone jack on the 2 gets some people.)