Instead of ranking them—since, theoretically, I could be really excited or not at all excited about all of these events, and thus my No. 9 event could theoretically be not far off my No. 1 event as opposed to being WAY off, as the lowest ranking might suggest—I'll just give a one-word summation of how I feel about each one:
Summer League Boring
Training Camp / Pre-Season Meh
Regular Season Interesting
All-Star Game Disgusting
Trade Deadline Exciting
Playoffs / Finals (Celtics games) Exciting
Playoffs / Finals (non-Celtics games) Meh
NBA Draft Underwhelming
Free Agency Intriguing