If I were to make my own transformers movie

Do it like they do on the Discovery channel.

My version of DOTM would have not done the moon landings and instead of the flashback to the war on Cybertron, mine would have gone back to the War with Unicron and shown the thirteen primes battling the chaos bringer with Prima sacrificing himself and using the Matrix to defeat Unicron.

Jump back and the story would show the Autobots detect a faint energon signature drifting near the earth and so use their shuttle to find and collect Prima's body (they are all shocked to find out that it is Prima). Optimus uses the matrix to reawaken Prima and we get some scenes between the two that mirror the scenes between OP and Sentinal.

I would show Megatron in Africa again and reveal the Laserbeak has been spying on the autobots for soundwave and tells Megs about Prima's discovery. The cons then attack the bots trying to capture Prima but then Optimus is surprised when Prima switches sides and kills his two protectors (Ironhide and Sideswipe). When Optimus confronts Prima, he tells Prime that he is not Prima but is instead Unicron who's spark had possessed the Original primes body after the matrix had put his own (planet sized) body into stasis in the last battle and intends to find a way to unite with it again.

Megatron meets with Prima who offers the decepticons help if Unicron will help them conquer the earth and destroy the rest of the Autobots. Megatron sweetens the deal by showing Unicron the space bridge that the cons have built (its the reason why the cons havent bothered the bots for years between ROTF and DOTM).

There wouldnt be a Autbot exodus scene in this and the final fight would not take place in a city (seriously we did that in the 1st film.) but instead take place in Antartica (nice change).

There would be no nest or military involved in this fight. Unicron and Megatron activate the space bridge and start to pull Unicron's body through the portal into orbit over earth. The autobots then attack with Optimus taking on megs and Unicron while the bots try to destroy the space bridge's power supply.

Optimus beats Megatron easily (since he was seriously damaged in last film) and takes on Unicron who gets the upper hand by slicing OP's arm off (like DOTM). But Bumblebee, Ratchet, Hound and Cliffjumper take down the space bridge which explodes, destroying the half of Unicron's body that had already passed through the portal before it collapsed. Unicron gets distracted by this turn of events and gives Optimus the chance to mortally wound him.

continued in next post.

Continuing.....

Unicron's spark then jumps to Megatron (who was unconsious at the time) and then charges at Optimus who then kills him (in the same manner that Megs dies in DOTM). After the battle Optimus has a brief converstation with Prima before he dies.

Autobots:

Optimus Prime
Bumblebee
Ratchet
Ironhide
Sideswipe
Arcee
Hound
Cliffjumper
Wheeljack

Decepticons:

Megatron
Starscream
Soundwave
Thundercracker
Skywarp
Laserbeak
Barricade
Breakdown
Shockwave

and

Prima/Unicron

Charlotte Mearing.