That leaves us with destroy and synthesis. Destroy is what I use when I'm being nostalgic and thinking of Shepard's relationships with her friends and lovers, imagining what it would be like if she adopts that little krogan baby with Garrus or if she goes to hang out with Jack at a club, dancing as shittily as she possibly can. It's my go-to ending when I want that last little breath of hope - that Shepard still lives.
But honestly? Synthesis is what I think my Shepard would have wanted. Destroying EDI and the geth, after securing their loyalty, would just be unconscionable to her. And it would supposedly bring a peace (if that stupid little Star Child asshole is to be trusted) that none of the other options would. The Reapers have one thing right: organics, no matter how advanced, will eventually resort to war with those it disagrees, so destroying the Reapers would not end the cycle, and after a millennia or so of the Reaper overlords under the control ending, the organics would feel somewhat enslaved or overly monitored, ultimately ending in another all-out attack and probably their (organics) complete destruction. Sure, it's speculation, but hey, this is a science fiction video game. What do you want from me?