Just use the stock cooler or some cheap air cooler(be quiet! Pure Rock Slim should fit no problem and is $40 for example.), unless you think the looks are worth $100+ as the 3600 won't get any advantage from being on a expensive cooler, AIO or Air.
Also some bigger coolers from Scythe and Thermalright seems to fit the case according to the sizes on PCPP, but are apparently really expensive or unavailable in Canada, maybe those are worth a looking if you can get one for cheap in case you want more options.
In my opinion AIOs are useless for these new Ryzen CPUs, even some cheaper air coolers can max out the 12c part while staying at usable temps.
Also any reason why you can't reuse the AIO you already have? if you can reuse then just don't get a new one, no need to do so.