I almost always play a human Spectre.

As for preserving of of sythentic life I always choose the ending where Shepard sacrifices [b]her[/b] life to merge with that big energy beam thingy that makes every sentient being techno-organic. It is the happiest and saddest ending of them all.

If your plan is to have the Reapers come back then you are ignoring all four endings from ME3.