Data doesn't have a spirit, he's a toaster.
Hey bbjeg, this is a good poll idea, "what character(s) most embody the spirit of Star Trek?"
Data went through finding and defining himself, gave his all in the name of exploration, surpassed his boundaries, and sacrificed himself for loved ones. He could personify Star Trek's spirit, even though he doesn't have one.
I thought about the poll and I'll probably end up running out of space to accommodate everyone (20 choices is the highest I've gotten so far). Other than the main cast you have choices like Sarek, Shelby, or Rom that could fit that bill.