The thing is, obviously not *every* decision has to be taken into account as not everything you have done would directly have an impact on the final decision. My main problem is that the ending will be the same three choices no matter how I played.
I had a think about this while discussing the same thing with a friend and this would have been the endings possible if I was in charge:
Paragon / Destruction: Destroy the reapers and the Citadel, save the relays. Galaxy enters a new Golden Age of peace and prosperity. Shep "gives his life" in the destruction of the citadel but his entire paragon actions somehow have his allies save him before the citadel is destroyed.
Renegade / Destruction: Destroy the reapers and the Citadel, save the relays. Galaxy enters a new golden age of peace and prosperity. Shep sees the smaller force destroyed and goes down with the Citadel with no one to help him.
Paragon / Control: Shep chooses to control the reapers by “merging” with the panel but the Citadel is destroyed in the “control-blast” as well as the relays. Shep orders the Reapers to crash/destroy each other and rid the galaxy of the reaper threat while his “essence” is seen being destroyed along with the Citadel and all Reaper existence. The united allies are shown working towards rebuilding their own Mass Relays.
Renegade / Control: Shep chooses to control the reapers by “merging” with the panel and becomes a reaper-esque husk over the controls. The Citadel, relays and reapers “survive”. Shep controls the Reapers to gain unlimited power over the galaxy. The allied military forces are shown being destroyed and all other life becoming subdued and indoctrinated.
Paragon / Synthesis: Shep gives his life to unite the galaxy in a new age of biotech life. The Reapers are not destroyed but leave as all life is now partly synthetic. The Citadel and Relays survive. Quarians are shown removing their masks, interacting with Geth in a more “human” way, like Joker and EDI. Free will and the galaxy are saved.
Renegade / Synthesis: Shep gives his life believing he will survive. He and the reapers are both destroyed not all species are transformed, only humans. War continues with Synth-humans and organic species.
Obviously there would be more to it but I couldn't be bothered to think up that much for it.
What's really sad is I genuinely think *anyone* could have come up with better endings then they did. There was just nothing to them. Weak.