There is no somple answer to the question, the best glider is the one you can afford. Most glass 15m gliders are fairly easy to fly, if you trained in a glass trainer.
I trained in a first model twin Astir, and have never had an issue converting to other glass gliders.
Points that maybe relevant are, nose hook for aerotow, powerfull airbrakes rather than flap only brakes, and tailplane with elevtor rather than all moving.
Best optionis to try different types before you buy.
In the lower cost glass end, The Astir CS, Libelle and club Libelle, Dg101, ASW19, Pegase, Hornet and Standard Cirrus with fixed tailplane are all good options.
If you can afford it, an LS4 or Discus.
Next comes the Mosquito, Mini Nimbus, DG200 LS3 and ASW20, All easy enough to fly
Generally speaking the newer the glider, the easier to fly.
I recently bought my first glider, having 220 hours, I bought a DG 200/17C.