Saddest:
Optimus Prime (G1)
Dinobot (Beast Wars)
Starscream (Armada)
Prowl (Animated)
Skids (IDW)

Shocking:
Ironhide, Prowl, Ratchet, Brawn, Wheeljack, Windcharger (G1)
Depth Charge and Rampage (Beast Wars)
Blurr (Animated)
Breakdown and Dreadwing (Prime)
Bumblebee, Pipes, Trailbreaker (IDW)

 

So at the time I'd say Optimus' death in the G1 movie was sad, but because he came back to life and it set up the trend of Primes dying and resurrecting all the time in later shows it really lost its impact in context for me.

So now I would say Dinobot from Beast Wars, such a good episode and a really fitting death.

 

Animated Prowl. Just that smile gets me.

 

I won't say it was my personal saddest or shocking, but seeing G1 Wheeljack, who had always been so happy and fun-loving, sprawled on the floor and lifeless, with that permanent sorrowful look on his face, was a real kick in the gut.

 

Saddest is easily Beast Wars Dinobot and Animated Prowl.

Shocking for me is Beast Wars Tarantulas.

 

Most shocking to me: Pipes. I completely agree and once again saddened for what happened to the plucky little guy.

 

Most shocking and moving death (not saddest, maybe, but moving) for me was Ravage in Beast Wars.

 

I was honestly kinda shocked by Terrorsaur and Scorponok's deaths in Beast Wars. Wasn't expecting those two to just go like that...

 

Scrounge. It was a bit brutal, letting himself be melted alive so Blaster could escape.

Actually, the whole 'melting living beings alive' could easily be seen as a bit OTT.

 

Armada Starscream takes both categories for me.