Both are really high quality racks. They're in a totally different league as AP/RBI/C-serpents/etc.

I have experience with FB, but also like ARS.
The FB racks have removable ventilation panels so you can switch them out accordingly to your environment.
Their racks are stainless steel so it's easy to clean. I think ARS is powder coated racks right? That may look and feel better than the FB rack.
The tubs and heat for both are about the same.

Jeff from Freedom Breeder is great to work with. Excellent service.

My rack has no issue, but I've heard that some FB tubs don't slide as well as the ARS.

Either way, you can't go wrong.