Hi , I am Nokia / Microsoft user from lifetime .
With uncertainty on Windows phone many friends suggested to move towards IOS .
Please give your valuable feedback
I too have been using Windows phone since Windows Mobile and moving on to 8.1 and then Windows 10 Mobile. I switched to an IPhone 4 and used it for 2 years when Microsoft was sorting out their move from Windows Mobile 7.x to 8.1. I also tried recently to go to Android with a Samsung S4 running lollipop and that lasted only about 4 months before I moved back to Windows 10 Mobile.
Since you are a lifetime Windows phone user, you need to consider the following if you want to move to iOS. Personally I cannot get used to the Apple ecosystem for the following reasons:
1) iOS has a totally different file structure which means that moving files to and from phones and sharing files between different apps require a totally different approach. You cannot just drag or copy files using the file explorer. Each apps has it own sandbox and keep the files for that app in that sandbox. So, apps do not normally have access to files of other apps. Sharing and moving of files from phones to PCs/Macs are normally done using iTunes, iCloud or emails.
2) if you have lots of music or videos on your phone, then moving them to iOS may not be that straightforward because iOS don't support a lot of audio and video format. For music, you will need to convert your files to AAC and for video to H.264 format. These are high quality audio and video format but may not be what we have on our Windows phone.
3) As mentioned, iTunes is the foundation of iOS for managing your music, movies, photos and apps. It is a stable and mature software but I cannot get used to it. While many people found iTunes easy, I personally prefer the simplicity of Windows' file explorer with the ability to plug in multiple devices into my PCs and move files around easily. iTunes is too cumbersome for me.
4) iPhones are very simple to use but it also means that you cannot really customize how you want the screen to look like. You do not have live tiles or widgets or home screen. What you have though is rows of apps that you can move around. I much prefer the ability to customize how I like my phone to look like.
5) iPhones do not support all the normal things that we are used to such as SD cards, usb, headphone jack, and removable battery. Some of these may be important to you. On an iPhone, you rely on internal memory, uses lightning port for charging and headphone (assuming you are getting the new iPhone 7). You also do not have many iPhone models to choose from, basically just the one model with different size screen that remained unchanged over the last few years.
Because of the above, I do not see myself being able to get used to iOS. Android phones are much closer to our Windows phone in operation and customization, but I still prefer Windows.