Buying LS3a or ASW20a? ~$25k cross country glider. Which one and why?

First questions nobody asked.......
Where are you flying?
How serious?

I can only comment on 20's........
20a, fantastic flaps......early flying season, come in very high on final, do full landing flaps and full dive brakes.......drops like a homesick brick.......
But, elevator is not auto connect.......know of a ship trashed because of this.
A 20A or C, limited to 9pounds..........fine if eastern thermals. Screwed if fast conditions.
Sucks to western thermals or ridge......trust me, I have been beat in eastern ridge in a nationals......I had local knowledge so made time on gap climbs, watched heavier gliders run by on long ridge runs. Yes, ran against "DG in a LS6" and,others.
Flying ridges or western thermals, maybe a 20B.
All the 20's can be helped with winglets.
I have my preference, but I am biased partly because I was "beta boy" on lots of testing for 20 and 24 winglets.

In your price range.....I will say a standard AS ship......partly because if you learned on a SGS, control harmony is similar.
I can't state for other glass single seaters.......

As stated before, in your price range, a flapped ship is likely borderline a rat.
Bad?.......ask Daniel on his performance on a "rat ship" I know of last year.
Crazed surface THAT IS SMOOTH can do well.
Most of a result is the "nut behind the stick".

Just my opinion.
Best I ever did was first page on the SSA ranking list.
I won't say I am a "mover or shaker"....,,