It's really hard to say, everybody has his/her favourites....
The Rocca store, You mentioned, is not much favoured in this forum but then again...it depends. Anyway, if You buy fish from it, take another look and if You find several dead/sick fish, think again. Btw, aquarium technics in mentioned shop is very good.
Personally i like most shop located in Mustamäe, at Sõpruse 222 (red, high house) and a small shop near it (where the Kännu Kukk restaurant used to be).
Mulla street. shop is also said to be good, Tartu mnt. shop likewise.
You see, it's really hard to say what's best
Whatever Your choise would be, i'd reccomend using a quarantine aquarium for new fish for some time. You could never know.This practise has once saved my tank...