@Patrick Kennedy
If you go back to one of my first posts to you here, I recommended subs because you expressed, at some point, general contentment with your overall system.
If you are happy, in general, with the overall SQ you experience, I would stand by that recommendation.
If you are not, and you would prefer a better overall experience in terms of SQ, then your Front 3 should be the focus. I agree with
@AcuDefTechGuy and his recommendation, too.
I recommended the subs based on your reply when I asked about HT vs Music, and how much critical listening you do. I think you can find some great speakers for your Front 3, without dropping the whole budget. But if you choose to go speakers first, I strongly advise taking more than just a half-step forward. We can drop recommendations all day, but only you can decide what is right for you.
Sub(s) will improve your HT experience pretty significantly, especially if you have taken care in setting up your Front 3 and are getting from them the best performance you can.
Then there is the flip side.

For now, I will just say I agree with Shady's earlier assessment that you can find better speakers. My preference in 90% of cases would be to look for 3-way Mains and Centers.
I'll leave it there for now.
Cheers!