Ok I have this:

https://www.smith-wesson.com/firearms/mp-15-sport-ii-optics-ready-m-lok-handguard

I have made a few additions.  Most notable to this conversation would be a K2+ grip.

I like it.

I even like the M4 style stock except..... Man, that thing is cheap.   It doesn't feel nearly as good as the handguard or K2+.  Its clearly an inferior material.   It rattles too.  I managed to attach a very small piece of soft side Velcro inside and that fixed it but it feels like a ridiculous solution.  It feels terrible to the touch too.  I don't want a different shape or style or stock.  I like the size, shape, and the natural quick grab to adjust.  I just want something that doesn't feel like a cheap toy.  The only thing I might change would be to have a QD where the horizontal slit is for a sling.   Doesn't have to be there though.  Any suggestions on what I should look at?  I want a material that feels closer to the Magpul handguard and open to other suggestions.

The B5 Bravo would be my vote.

Magpul CTR or MOE SL, Bravo B5, BCM Mod 0, Vltor has some great offerings. Honestly the market has so many choices out there and it makes it hard to pick, but those are my top ones that I have felt/used.

BCM gets my vote. They lock up tighter than a virgin prom date.

I never paid much attention to Magpul stuff until I saw the CTR locking feature and got my hands on one.  Now I have at least 6 of them.  I like them a lot.

I have a CTR on my SBR and really like it. I only mentioned the B5 because the OP said he wanted something similar looking to a M4 waffle stock.

I'm a fan of the BCM stocks.  They lock up really tight without the need to be "locked".

LWRC Compact (not the ultra compact).

That B5 looks like just what I was describing.   QD on a better quality M4 stock.  
I don't like the Magpul stocks.   Mostly the way they adjust or have the adjustment protected (blocked).   That B5 looks nice.  I may have to see if I can get one in my hands to check out.

If you already have a Magpul grip and Handguards, get a Magpul stock too.

I like the CTR best, but all of 'em are good.

If you want to stick with a waffle stock, Colt and LMT are the best quality by far.  Holler  if you want one, I have a few extra.

Another vote for the ctr here.  I use and recommend them almost exclusively for carbines.   Good looking, tough, and tight lockup.