A few short years ago I had no idea humidity affected plants, so if you're asking this question you're way ahead of where I was.
Most houseplants are tropical plants so they thrive in humid air (there are exceptions to this, like desert cactus, so you can always look into specific varieties to see what they like). We're talking 40% or higher humidity for tropical plants.
Depending on where you live that might mean your plants would benefit from a humidifier. If you're like me and you live in the more humid PNW, our home is naturally at about 40-50% humidity (we actually have a dehumidifier we use in the summer to prevent mold), so I don't use a humidifier.
If you live in a dry area, I would definitely look into getting a small humidifier to put near your plants. While your plants would probably love it as humid as you can make it, I don't recommend going much above 55% or you'll risk mold growing.
What about misters? Misters actually do pretty little to increase the moisture your plants feel unless you are misting several times per day. It's likely not making too much of a difference, but it can be a nice supplement to already humid air. And I think it makes my plants feel a little extra love :)
If you have any questions, drop them below!