The brand is too general, so let me guess, I would say maybe Oceanic Atom 3.1 versus Sunnto D4i.
To answer your question about "better/worse between a Suunto and an Oceanic in terms of interface or features.." I noticed something that,
The Suunto D4i is actually recommended dive computer for every leisure diver, I mean to fun or recreational diver. So, no matter level of skill, expert or newbies, it is totally great. of course it is also depend on the price range that people could afford it. Furthermore, the computer is readable along with user-friendly display, very easy to read via user interface together with the documentation.
But, the Oceanic Atom is loaded with numerous advanced functions and could be recommended dive computer for technical diving, or expert diving together with the complex user documentation. It provides the diver a chance to stretch out our under the sea activities to higher limitations. Oceanic Atom 3 is actually all around dive watch computer for expert divers, because it has all possible capabilities to dive with 3 gas mixes and also to handle 4 dive modes. I do believe that newbies will discover this dive computer complicated.
So, the verdict, I think that, no wonder a certain dive instructor will talk about the Oceanic, because of it is made for the experts.