Just my $0.02, but after researching ATS. As well as seeing tanks running ATS as the only means of filtration beyond running carbon to polish the water, and the longterm success people in my local club have had. I personally would opt for ATS over fuge. Obviously this is much easier with a new tank setup, or I you plan to do a major overhaul of your sump area.
If you want to use this as a primary means of filtration. I would vote ATS. Between the increased water flow and contact time, as well as growing a simpler form of algae. An ATS that is setup correctly and has the lighting adjusted to grow algae without burning it should always be able to outcompete a ball of cheato that can only contact some of the water flowing through the sump chamber.
If you just want an area for pods to grow, or if you have an empty fuge compartment in your sump, then I'd probably go the easy route of hanging a light over some cheato.
Not intending to knock refugiums, they are commonplace for a reason. But once commercially produced ATS units become readily available. I think it will likely become one of the most popular forms of filtration in the hobby.
The only reason I am not using an ATS myself is dealing with getting materials and building it. Followed by modifying my sump setup. While it is a project on my radar I haven't reached the motivation level required to undertake it quite yet.