I can offer some impressions of one of the glider types you have
mentioned. My background, I flew a Pik 20E for 10 years, last year I
purchased a DG800A (18/15 metre span, air frame same as DG 800B) and
have about 60 hours in it. I pursue recreational cross-country soaring
only, no competition (except the OLC), and I am very please with the
new glider. The transition from the Pik to the DG was smooth and
quick. In my opinion the DG is the better handling machine by a slight
margin. The major points I noted about the DG we

1. Excellent cockpit ergonomics, 10 hour flight and still comfortable
2. Good visibility ( plus warm feet, even during winter wave flights)
3. Good roll rate, grooves well in thermals making it easier to centre
and climb efficiently
4. Excellent approach control with landing flap and spoilers
5. Increase in performance over the Pik was quite an eye opener, the
18 metre span coupled with lighter weight and lower wing loading of
the DG opened up weak weather scratching ability that I did not
previously have, while it still performed well at high speeds.
6. Taxiing ability, even in 35 knot crosswinds is excellent, precise
and fully controlled. This is entirely a function of the well designed
DG tail wheel.
7. Low cockpit noise level at high speeds
8. Logical and easy engine operations, although a lot more complicated
than the simple mechanical system of the Pik

I have not flown any of the other machines you listed, but I did
compare the numbers to contrast the Ventus 2Cm and the ASH 26E when I
was in the market. The fixed 18 metre span of the 26E made it a
difficult fit in my hanger, the 13 liter main tank of the Ventus meant
that I would have to manage three fuel tanks, main plus 2 wing tanks,
for most of my wave flight launches. Both the 26E and the 2CM would
operate at a higher minimum wing loading compared to the 800. My
impression is that there is not much to choose between the three
gliders, it comes down to fine details and personal preference. I
would however recommend 18 metre tip extensions, if available, on any
glider you choose as cost effective performance increase.