While I have never taken a fully unsubbed break, I have spent roughly 3 months now doing little more than sitting in station, occasionally hauling a few ships around, and RPing.
I've moved to a new corp now and am hoping a PvP focus away from the nightmare that FW is will help me get back in the game. In general, however, the following two issues would help restore a great deal of faith in the game:
1. CCP getting a hold on (or at least an understanding of the depth of) the meta that goes on in their own game. Everywhere from FW to the mining barge revamp to their "entry" into the competative gaming arena, CCP has lately shown little comprehension of the degree to which their own players will min/max, sabotage, and trample all over the intended design of mechanics changes to assure their victory/profit/lols.
2. A return of an ongoing, living universe. While I am just as happy as anyone else to see the return of live events, I still have an empty spot in my heart for the old news articles.