Ideally you want:
A: Match all speakers, not Subs (but you want your Subs to match each other).
Or...
B: Match your Front 3, with a strong recommendation to match your Surrounds with your Front 3. Rears and Atmos can be something else, but hopefully closely matched. Subs should still match each other.
Or if you just can't...
C: Match your Front 3, and do what you will for the rest. (Hopefully you will still match your Subs!)
Re: Subs... Most Speaker manufacturers don't make great Subs. There are plenty of companies, fortunately, that do.
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
SVS, Monoprice Monolith, Outlaw, Hsu. Rythmik and PSA both get a lot of mention. On the higher end, JTR, Deep Sea, and Funk.
Mind... Subwoofers need to match your Room Volume (as in total open room cubic feet, not just the corner you listen in.) Good clean bass reproduction is a subtle but beautiful thing.
If your budget is tight, buy the best single sub for your room, which you can allow yourself to afford, and start saving for a second.
![Big Grin :D :D](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Multiple subs, placed smartly, help you get a better in-room response than any single sub will.
Hope this helps.