FWIW, I would take anyone's opinion that hasn't spent a good deal of time in both with a grain of salt. Virtually ANY change and transition makes you think that your old way was superior until you get used to it. It's human nature. People tend to see what they want and often that is the good things for what they are comfortable with and the bad things for those they aren't.
I actually have spent (and still do) significant time in both IOS and Android... I do have IOS devices despite what people here may think.
I can tell you truthfully and honestly that neither OS or hardware is just pure "better" in an overall sense. They both have their pluses and minuses. I've had a couple of friends that have switched, going both ways, and can relay a few things from their experiences and my own.
IOS -> Android
1. You will miss iMessage... nothing on Android is even remotely close to the convenience. The new RCS is close, and has nearly full carrier support so it will almost certainly succeed, but it isn't purely a Google effort so it will take another year or two. You
can have your text messages go to the computer too, but it isn't the same.
2. Hardware is kind of a wash with Apple if you stick with a Pixel 3 or an S10, there are pluses and minuses on all of them. Overall, I would say Apple's devices
in general feel like a better build, though once you put a case on them they kind of even out. The Apple devices tend to look better overall, but I don't give a flip about that, I want something that works, but it is a consideration if it will bother you. For example, the Pixel notch is hideous, but I don't even notice it anymore. The S10 is gorgeous, though, I haven't used it for any real amount of time (I don't own one). A quick IM with my friends just now seems like people haven't honestly cared either way.
3. Google's services take Apple's out to the woodshed, go grab a bite to eat, and go back out and whoop some more @ss. THIS is the reason I stay with Google, not the hardware. Google Drive and Photos alone will make you a believer in cloud services and show you what Apple NEEDS to be doing. My friends who have switched say this was the biggest loss going TO IOS (and they have tried to replace Apple's with Google's but it is never as cohesive as on Android).
4. Battery life on Android is a huge mixed bag... I don't care what any of the reviews and such say, IOS devices in a real world state seem to last longer for me. There are more options for Android, though, so you CAN get good battery life, but have to be careful. The Pixel 3 XL and Samsung S10+ both are good but overall I have heard complaints from many of the other phones with smaller batteries.
5. There is not Face ID on Android... a few have "Facial Recognition" and you shouldn't use it. Even the phones with it on there say don't use it. So you will use fingerprint. I loathe Face ID, though, so I don't miss it on IOS. However, I am one that likes to unlock the phone with the rear fingerprint sensor as it comes out of my pocket. If you have your phone on the desk a lot, you may be in the complete opposite camp and just be annoyed at not having it. Personal preference.
6. Most major software is virtually identical on both IOS, visual design aside. It used to be that the IOS versions were much better than on Android, but that is no longer the case for major vendors and, especially some of the European companies, has flipped. But no matter, I'd say if you stick with major developers you are fine. The Play Store is WAY less curated and has a bunch more junk than the App Store, but I don't really just look for sh!t to install so it doesn't bother me. If you are one that just installs stuff to test it, might be a consideration.
7. The desktop to phone to tablet transition (i.e. handing off what you are doing) is better on IOS. I don't have to do this often, but when I do I can say IOS whoops some butt in this regard.
8. Everyone said to give it time, going both ways. You have to get used to and immersed in the ecosystem to really feel it out. For instance, my Android to IOS friends report trying to hit the Back button over and over and over for weeks and weeks. My IOS to Android friends kept trying to find it in the top left.
9. The manufacturer overlays are NOT what @Durosity claims any more, sorry bud. They are far lighter weight than in the past. The carriers do all like to add their stuff in but Android allows you to "freeze" those apps so they are basically non-existent. Or just buy the phone unlocked and you won't have any on there to start with (that's what I do and recommend).
10. Updates - mixed bag, but in general the Pixels are on par with IOS and even faster, all others will be slower updating than you are used to having with Apple. Some smaller manufacturers seem to drop support quickly. Samsung used to be known for that but have been better the last few years. But still you have a 6-month delay from the Pixels. Long story short, if you don't get a Pixel your Apple-esque way of getting updates immediately after launch is gone.
11. Google Assistant is way better than Siri and Alexa for all things except HomeKit. Actually, Google's HA is very impressive and arguably more impressive than Apple's on the back end, but using Indigo with it won't be viable until Alexa support is added and new hardware definitely favors HomeKit.
In short, nearly all haters of each platform haven't spent the time in each to truly know the differences and advantages and disadvantages. There are a LOT of zealots out there and it is probably even harder to get an Android user to honestly evaluate IOS than the other way around - too much animosity towards Apple for some made up or imaginary reason. Both are excellent, both have their advantages and disadvantages, and you just have to see which "fits" for you. I like both, except for Indigo support, then I like Android better. LOL
Adam