What you have to remember here is that it is not the phone per say that causes the issues with the forum usability.
It is down to the browser being used by the phone and how it is updated, if at all. I use a Windows phone and never use any Apple product and use one Android tablet with OS v4.2.2 (Samsung Galaxy Tab 2 10.1"). I had three of MS phones, Lumia's 610, 630 and the 650. The 630 I gave to my brother so I could use the much better 650. The 610 barely coped with stuff and is an older Win version of course.
The 650 is working absolutely fine under Win10 and I have no problems with the forum except on odd occasions the placement of the cursor for editing is a tad off. Usually it is OK.
So it is the browser that causes the problems. The thing with MS phones is that the company didn't want to release details of their OS to marketing people and those who write the apps because their secrets for the OS would be available to all and they very much fear hacking into business servers if this were released.
Android OS is much more open to the public and therefore easier to write for. Being open source means the code it is written in is freely available to anyone who wants to utilise its innards for apps and the likes. For this reason alone it is far superior to those who write these things. For the business world it is absolutely useless.
As for the forum we use here it is not written specifically for any particular browser but will be tested within the most common and up to date versions. MS, however, don't update their browsers anywhere near enough as the others do. So it fails miserably.
Hence the reason for the MS OS failing in the phone market.
Personally I would never, as stated above, touch any Apple product, for many reasons but mainly because it is far too proprietory and not interchangeable with other hardware or software.
Android is a weird OS but is stable and is popular enough for it to carry on for a very long time in the future. It will be difficult for any paid OS to catch or usurp it. MS failed miserably and have recently announced MS phones will no longer be produced.
Personally I would probably go to Android as the only viable option which allows connection to my server through MS Exchange and my own network. It would also have to cope very well with remote access. The rest of the stuff like cameras and the likes... well, I have a perfectly good camera for taking shots professionally so the 'extras' are irrelevant.
Apologies for the longer than planned text but the upshot is the phone is not to blame in itself it is the OS and the browser within in particular.