I always tried to avoid that problem in D&D by using the best of 4d6 method to generate the stats and giving the players a background which justified some decent equipment to start with, that way they would at least survive the early adventures. And then I could have fun killing them later :)
I used 4D6 throw out the lowest in my campaigns.
Let the players have a small budget to buy stuff, and they could make up a history based on whatever the current scenario was.
I hardly EVER killed a character... We had very complicated story lines, lots of NPCs, mystery, Dark Arts, Aliens, intrigue, war, treachery, daring deeds and True Love.
And a fair amount of foolishness and humor thrown in for good measure...
( Once i was stuck for an idea... couldn't come up with ANTHING for that night's run...SERIOUS Writer's block. Our party of Victorian Adventurers is deep in Inja....and while guesting at Colonel Mustards hunting lodge, one of them sits on Mrs. Mustard's pet budgie, killing it. The run turned out to be VERY memorable, as they raced about trying to keep the good Colonel and his Lady from finding out, and then replacing the budgie. Took all night, they had a wonderful time doing it, and my reputation was SAVEd.
For another week! LOL!)
I'd slaughter NPCs with abandon, but killing PCs was too much like killing a friend.