Your asking for a sane dictator which is an oxymoron.
Especially since one can argue that being dictator was the biggest factor causing Stalin to act like a mad man. Same as how cult leaders tend to turn into utter nuts when they gain complete power over everyone in their cult compound.
Now it is interesting to consider how things would have gone if Stalin were the most powerful man in the USSR, but not a dictator. Say if the Leninist revolution never happens, and the Bolsheviks, working with the Menshiviks and the left-leaning SRs win power due to the Soviets gaining power democratically from the Provisional Government. The Bolshevik-Menshivik-SR coalition would then dominate the Soviets and Stalin would be an important figure in this coalition (as he was before Lenin returned to Russia and pulled the Bolsheviks onto a different path) and it is possible that he might rise high enough to be elected leader of this democratic and socialist Russia.
Of course, even if Stalin had never become a Leninist as he did in OTL, he'd still be a Marxist. And a passionate and ruthless one at that. So however things go, he'll have his ideological blinders which will make it difficult for him to accurately predict the behaviour of capitalist republics (especially the United States) and which will mean he'll commit to bad economic policies, so it won't all be flowers and sunshine. But I suspect a non-totalitarian USSR led by a less paranoid Stalin would mean a much, much stronger USSR.
fasquardon