My chassis use is primarily for .22, Vudoo and Bergara.
I have owned/used the following:
MPA Hybrid
XLR Envy Pro
MPA BA Comp
MDT HNT26
MPA BA ESR
The MPA Hybrid was my first serious chassis for .22. I selected it for its low weight, but needed to put a lot of weight into the fore-end to come close to getting good balance with the 20" MTU profile. The accessory mounting is a bit limited, but overall it is a nice chassis with no unneeded weight. The method of retaining the weights inside the chassis is a bit unrefined, and I had to grind down the screws to prevent contact with my barrel. I swapped the cheek rest for the low-profile version as I like my head to be as vertical as possible when shooting. I had issues with making contact with my support bag and magazine, causing failures to feed. This was exacerbated at the time due to my 20" MTU profile not quite balancing forward enough of the magwell, so I was driving the gun pretty far forward for barricade/support bag shooting.
I then tried the XLR Envy Pro with a C6 stock for a bit (I think mine was the Vibbert "comp" model). I really liked the idea of the adjustable thumb rest, sportwatch timer mount, MLok attachment provisions, and long barrel shroud. Overall a pretty nice chassis. The magwell flare helps prevent contact between the bag and mag.
The BA Comp (I don't remember when or why I picked it up) was pretty much just a slightly heavier Hybrid with some more weight in the rear for the adjustment knobs, and a cleaner attachment of the NV bridge. Pretty much otherwise the same as the Hybrid.
I got the HNT26 for a lightweight stock for an NRL Hunter rifle for my kid, but wound up dropping a Bergara B14R into it for him for PRS Rimfire. The B14R, with an 18" standard barrel tends to be ass heavy in most chassis, even with full internal weight kits. I try to avoid external weights on my competition rifles, as I want it to be able to work through narrow ports. The B14R in the HNT26 balances pretty decently, which was nice. The HNT26 is a pretty basic stock, on the higher cost side. When I rebarrel the Bergara it will most likely be going into either the Envy Pro or an MDT LSS-XL with an extended NV hood.
I really like the MPA ESR. All the good things of the Hybrid (I pulled out the adjustment knob hardware on the stock to drop ass-end weight), but with a longer fore-end with MLok attachments. Mine is the older version, before they integrated the barricade stop attachment points on the magwell, so I got one of the Grey Ops bag stops, and it has completely eliminated my issue with MPA chassis. It's nice that it's integrated now, and I will be getting that version if I decide to completely build up a backup rifle rather than just bringing a spare barreled action. I like the MPA grip, though I do consider doing a little dremel work to the first finger undercut. As with the Hubrid, I use the slim cheek piece, and I invert the buttpad to allow a deeper placement on my shoulder. I do not use a bag-rider, finding them to be unnecessary weight with .22, and without it I have a little more leeway on rear-bag height, but that's not really all that significant. I'm still playing around with thumb-stops and NV hoods/barrel shrouds to find what I like best for support-hand thumb, but that's just fine-tuning. I chose this over the Matrix simply to be able to balance the gun at lower weight. I like a lot of what they have going on with the Matrix, I just would like to see the stock be more like the Hybrid.
Anyway, that's my experience.
