Honestly, you should really decide what exactly you need out of your device and then make a decision. Yes, there is an app gap. But do you REALLY use any of those apps, I know I don't so the "app gap" doesn't bother me much.
People always talk and compare platforms with the assumption everyone uses their devices the same or need the same things. I know several of my friends that have gotten the latest and greatest devices (Note, Galaxy, One Plus One, iPhone 6) just because it can supposedly "do everything." When it comes down to it, I observe how they use their devices and they are not even utilizing a quarter of what their devices can do! For example, the latest Note can do a "picture within a picture" app multitasking thing. The person I know that has it doesn't even know that feature exists! My other friend has an iPhone 6. They STILL don't utilize the cloud sync features to the fullest. Facetime? they don't use that either. Several of my friends have these new flagship devices and all they do is text, check facebook, and surf the internet. They don't game, they barely download any apps, and they don't even explore all the new "features" available on their devices.
Bottom line, don't let others persuade you to switch because of features you know you don't use. If WP is lacking in something you just have to have, switch to another OS. Decide what YOU want/need out of your device, not what other people "brag" about what their devices can do (and probably don't even use). If WP meets those needs, no need to switch. If not, do some research and find what other platforms offer you that meets YOUR needs.