I am an old small time audiophile, so I still have dear, old two channel stereo fro my music. I do have a 5.1 A/V setup for TV.
In the stereo world, us fans always have lusted for the two best front L&R speakers we could afford for accuracy & musicality.
When you introduce a center channel, it should be very good because surround systems typically direct 65-70% of the audio information. The center channel purpose is to firmly anchor the dialog close by the TV screen at the front. Of course, the occasional but oh so important brief dramatic surround effects are wanted by surround home theater fans. For them, having a high quality sub woofer is key.
If you are going to wind up with a center channel, the importance of the front L&R is diminished substantially because so much of their audio info is then sent through the center channel. As far as the front is concerned, the center becomes the most important speaker.
There is an alternative for the front. If you get good front L&R speakers, you can just omit the center channel & retain the greater amount of audio info for the L&R. That is called having a "phantom" center.
When it comes to speakers, as an old small time audiophile, I am very quality oriented because it is the speakers that are the typical source of different sound character, not the receiver. The electronics are supposed to perform with a neutral sound & by & large they do that.
So, you have HTIB speakers of which I typically don't think too much of as far a quality goes. HTIBs are very popular because they are rather affordable. My opinion is that they all try to do too much for the dollars spent, so they are temporary solutions.
Quality speakers do have a certain entry level cost. No miracles exist. But those of us "into sound" regard them as only seemingly expensive up front because relatively affordable speakers will give pleasure for many years. so, a bargain in the long run.
We have had many threads here with suggestions for searching for speakers at various budgets; such as $1000 or $1500, etc. There are lots of resources.
Sorry to project the idea that speaker upgrades for you is just beginning a whole new game. Nonetheless, we feel it is worth it.