From a performance-per-dollar standpoint, 120mm AIO coolers aren't a good value based on my experience with an EVGA CLC120 AIO.
And their modest thermal capacity only make them suitable for fairly low wattage CPUs (like an AMD Ryzen 3700X, 65W TDP) unless you tolerate more fan noise from a faster spinning fan.
A well designed 240mm AIO is a much more capable cooling solution. Some of them aren't much more expensive than 120mm AIOs so if there's room in the case, the 240mm models are a better option. I am currently using an Arctic Liquid Freezer II 360mm, Liquid Freezer II 280mm, CoolerMaster 240mm, and EVGA CLC240 in different builds. The EVGA 120mm AIO is gathering dust in a closet.