gfyrasng, congratulations on deciding to pursue a DIR approach to diving. I think you will be glad you did.
There are quite a few brands of gear that work for the system out there now. What's important is that things fit, work together, and have the right amount of lift for the kind of diving you are doing. I don't know what size your wife is, but if she's on the small side, DSS (and I believe Halcyon) make small plates. DSS, I know, has a wobble-stopper setup that means you don't have to use a single tank adapter to secure your tank -- I think Oxycheq might have that, too, but I'm off Oxycheq gear myself because of customer service issues. DSS has grommets in the slots on the plate, which make adjusting the harness a little easier and protect the webbing. Halcyon has the new Infinity system, which permits adjustment and easy entry and exit from the harness, while preserving the location of the canister light and left hip D-ring, but the system is exceedingly expensive.
If you are interested in buying an entire rig at once, I would recommend DSS, simply because Tobin will take the time to make sure you buy something that will work for your wife. (Or for you, when you get that far.) He won't sell you something just because you want it (which sometimes annoys people, but I like it). Peter and I have a lot of DSS gear and have never been unhappy with any of it.
But the bottom line is that you have a lot of options, and what you choose will depend on what you prioritize and how important budget is to you.
If I can be of any specific assistance to you in this transition, please feel free to PM me. I'm happy to give any advice I can, or to give you ideas on how to get your education done when you get that far.