Depends on the 120mm AIO.
Generally, in the 120mm space, an air cooler would be the simpler/smarter idea - 120mm's aren't exactly great.
I assume the 120mm is more $ than the 212 EVO? If it's not, I wouldn't use it - even if it were free. Any AIO that can be sold for less than a 212EVO is almost certainly junk.
For the cost of a decent 120mm AIO, there are better air coolers.
For example; the cheapest 120mm AIO I can find is a LEPA AquaCooler 120 @ $45.
For $30 there's the Cryorig H7.
https://pcpartpicker.com/product/93Crxr/cryorig-cpu-cooler-h7
For $43 there's the Cryorig H5 Ultimate.
https://pcpartpicker.com/product/Ztp323/cryorig-cpu-cooler-h5ultimate
$42 can net you a Shadow Rock 2 from beQuiet...