Creepyoldguy's right on. You really need to get a grasp on the size requirements of rays, not only tank and filter but feed as well. Once you get the idea of how much food a large healthy growing ray may consume you'll understand. I personally can't stand canister filters, I still use them but hate the hoops you jump through to keep them clean. Definetly build a sump. I wouldn't have rays without one. Swapping out socks can be done faster then priming a canister with an external pump.
As far as bio more is better..... Can fit more in a sump.
Most of all if you're striving for top notch filtration you'll need to utilize several means (wet/dry, submerged, bio reactor) a sump will allow you options for all this and future upgrades (drip)