We shall have the transfert list live on the intranet in a few weeks, so we will all know exactly which bases are difficult (long) to get and which ones are not. It also depends if you are a CPT or FO.
All I know for the moment is Germany both Berlin and Dormund are lon waiting list.
"Latin" bases like Paris, Madrid and Milano, you can get them right away (except captain in Paris)
Captain in geneva : Forget it!
Waiting list to go to Scotland I heard.
easiest base to get : Gatwick !!