If you're not going to use gear that can benifit from the speed then about the only thing that you would gain going to a faster plan is more upload speed helping with it choking up when a phone or something is doing an icloud backup or similar.
Use a decent router, current iPhone and you will get the speed your current plan offers, not those low ones in the screenshot. Perhaps then upgrade the speed if you feel you want your spotify or netflix to download faster. No upgrade from 100 to gig will do anything speedwise for normal phone usage like scrolling thru facebook or liking cats on instagram.