Well, I made that switch about three weeks ago. Had an iPhone 6 since launch day and many iPhones prior to that. I've also used Android devices off and on for a number of years.
To answer your question, it depends
What I miss from the iPhone is:
* Receiving timely updates without waiting for OEMS and carriers to get their collective acts together
* Being able to walk into an Apple store and swap out a defective in-warranty device quickly and painlessly
That's about it really - If you're content with the IOS functionality and UI out of the box, knowing that you cannot deviate (much) from it, than you will be happy with an iPhone. If you have behavioral or functional requirements that the iPhone cannot provide, then go with Android. You will be much happier.
As an example - During the week I am in meetings constantly, and on weekends I'm attending events that I do not want to be disturbed while there. The iPhone has a "do not disturb" function but it doesn't allow for specific meeting times. Drove me (and other meeting attendees) crazy if someone forgot to toggle do not disturb on. With Android, there are any number of apps (I use Agent) that get much more granular and toggle sounds based on meetings/events in your calendar. Not important to everyone, but it is to me.
So.....you are trading customization for "do it Apple's way" with an iPhone. With that said, while you can debate the merits of their operating systems, both are robust and well done within their respective boundaries. Apple, HTC, and Samsung internal hardware designs are all excellent and get the job done.