With Belkin* recently coming out to play in the wireless mic romper room, how do you choose which is a good wireless mic system to get?
As well as Belkin, available choices (at least) are from Sennheiser, RØDE, DJI, Hollyland, SHURE, Audio Technica, Sony, Behringer and AKG, as well as a plethora of budget “no name” models, so the options for those who have little knowledge on the subject are wide indeed, and potentially very confusing.
It could be very easy to purchase entirely the wrong type for your needs without a bit of homework.

The easiest way to approach the purchasing of one then, is to break your requirements and considerations down into several areas.
To many people, the first and foremost consideration is probably price. It’s all very well to say you pay for what you get, but the simple fact is if you cannot afford nearly $500 for a top shelf Sennheiser or Shure system, then it is pointless looking at them.
Also important is to know is what devices will be using the mics? A smartphone with only a USB-C connection needs an entirely different setup than say a mirrorless camera that uses a 3.5mm connection for the receiver. And a GoPro is a different kettle of fish again as is an older iPhone.

Other considerations, but not necessarily in order, include range, battery life, technical info such as audio bit depth (which is an indication of audio quality), is it a dual or single transmitter system, do the transmitters have onboard memory in case the signal to the receiver is dropped, how are the mics attached to clothing (clip, magnets etc) and even the colour in some circumstances can be important.
Lesser things to look at are charging times, what connections are available (headphones in the receiver for example), does the case double as a charging station / battery and of course, the ruggedness of the unit as lav mics are prone to being dropped and even stood on!

Finally, where will you buy it from? Online might be cheaper in some cases, but if something goes wrong and you are on a shoot, it is often far better to spend a bit more at a retail location such as a Camera House, JBHifi etc so you can go directly back to the shop for a replacement under warranty for minimal disruption.
As an indication, my suggestions for different circumstances would be the following:
Compact with 3.5mm input eg Canon PowerShot Mk III RØDE Wireless Pro
DSLR/ Mirrorless eg Canon EOS R6, LUMIX S5 Mk II Sennheiser XSW Digital
GoPro Hero 8 – 13** (professional audio as against Bluetooth) RØDE Wireless Go
GoPro 12-13 with Bluetooth DJI Mic 3
Smartphone with Android (Samsung etc) Sennheiser Profile Single TX
iPhone (non USB-C) RØDE Wireless Micro
*I have yet to review the Belkin wireless system so it is not included in this list of recommendations.
**Note that Bluetooth audio is inferior to true wireless audio as it is highly compressed and has a far less range. For true wireless on a GoPro you need either the MediaMod or the GoPro Adaptor.