Here is a short summary of 3 styles of microphones with their pros and cons.
PROS – Some Handhelds have a switch that you can turn on and off. The best use of handheld microphones are for when you want the presenter to have full control over when they are heard and not heard.
CONS – A couple of issues with handhelds are most people don’t hold them the properly. These mics should be held directly in front of the mouth so you are always speaking directly into it. This allows for the sound to stay at a constant level and to avoid feedback. Also, you have to hold the microphone the entire time or use a stand for hands free. If you are an animated speaker and like to use your hands when you talk or if you are having any type of presentation where your hands are needed you need to take this into consideration when choosing your mic.
PROS – Lavalier microphones are great because it keeps your hands free for other things such as using a clicker for a presentation.
CONS – “Lavs” also pick up your voice if you turn around and your back is to your audience. You do need to consider that because it’s only attached to your lapel or button up it has to be positioned properly so if you turn your head your voice will be picked up clearly.
PROS – These are the mics you see many performers using on stage, singers, theatrical performers etc. Many conference presenters use them as well. These mics are close to the mouth therefore they are less susceptible to feedback.
CONS – Be sure the person who you want to use this mic is comfortable wearing them. Some find them intimidating and distracting. And men with facial hair, beards may have difficulty using them also.
Talk to your presenters and find out what their preference is and be sure to outline all of the advantages and disadvantages to them.