Poll
25%
17%
0%
8%
0%
50%
If we exclude the Sith that led it, I might have to say the Empire had the most dedicated members. I'm split between the Empire and Rebels, but leaning more towards the Imps...
The Sith were too unruly, there was no real dedication to the cause. It was a free-for-all of power.
There were Jedi who defected, of course. Still, the dedication shown by Kenobi and Yoda and Luke in the OT is extreme and definitely beats all. But with this thread I'm thinking you mean the generic masses.
And I know nothing of the Exchange.