Josh is 100% correct. It depends on the situation.
I'll give you an example. I've got a small audio recorder coming today.
When I am doing vlog style videos I will place the audio recorder above my camera and use it like a shotgun mic. A lav microphone isn't ideal in that kind of situation in my opinion as it isn't going to pick up any background noise. In a vlog you want to pick up the person speaking, but background noise from the environment is important too e.g. so they can hear you opening a door, switching a light on, playing music through your Bluetooth speaker etc. A lavalier mic would make it sound like I was in the studio.
There are other situations where a lav makes more sense. If I was recording a vlog from my car, a lav would be perfect in my opinion as it eliminates more background noise from the engine etc. It's also great if you are just sitting talking to the camera.
Bear in mind that there are different kinds of lavalier mics too, but most are designed to only pick up the person it is attached to.
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