You’re talking about relatively low budget chassis’ and stocks, with specific applications which aren’t so common.
None of them are bad, but none are what I would call “great” among their class of stocks and rifle chassis on the market.
I had the MDT LSS on a Savage Stealth Clone. Nice for a modernized hunting rifle, but didn’t meet my needs for a competition rig. The forend is short, and the half-hex bottom didn’t ride the bag well. The extreme angle on the magwell block ends too far forward, so the rifle didn’t ride very well on barricade bags. The forend is also very short, which is a limitation for running it on a bipod. It also felt very misbalanced with a Magpul PRS or UBR on the back. The balance was improved with a Luth-AR stock, but overall, then the chassis and added stock was too light to really ride recoil the way I wanted for field shooting. Hunting, sure, but not for prone, benchrest, or positional competition style shooting.
The Bravo is basically a plastic stock with an embedded half-chassis. There’s quite a bit of flex in the forend, and you’ll feel the fact the forend panels are bolted on. The forend of the Bravo is also quite short, again, limiting it’s utility on a bipod, unless you buy the extended spigot.
The Oryx is new, I’ve not seen one in person. I think it’s a diversion from many of the other chassis’ out there. At its price point, I have heard it is a good option.
I’ve shot a few Magpul 700’s, absolutely not a stock I want in my life - but you do a lot worse for the money. The magwell and feeding is good, and it doesn’t look terrible, but like most of these, it’s approaching a price point where I’d either go cheaper and bed, block, and free float a Boyd’s Provarmint, or save a little longer and get a bit better stock or chassis. Great deals are out there to be had on a lot of great stocks and chassis’, so I’d be waiting and watching, if I were in your shoes.