Stalin is unnecessarily maligned by Troskyite propaganda. Let's take a look at the hard facts:
- He was originally training to become a priest - thus he's likely to have strong moral principles, not negotiating with the Fascists as Trotsky historically did in a double-faced way (Remember Mussolini-Franco-Trotsky pact?)
- He would have focused on developing communism at a gradualist pace, as communism in a single country, instead of Trotskyite adventurism
- He was all for collective leadership instead of developing the Genius Trotsky cult. I think it's highly possible that under Stalin the Soviet democratic institutions would have started again.
- As a member of ethnic minority, being a Georgian, Soviet Union would have surely developed into a multicultural paradise instead of a Russian Empire v.2.1.
- As a pragmatician, the Trotskyite disaster of forced industrialization would not have come. Sure, the factories produced nifty T-34's, but Stalinist policies would have meant more and more motivated peasant conscripts to operate them.
-A Stalinist state would not be a militarist state, like Trotskyite USSR was, as the Red Army was Trotsky's power base
All in all, it's hard to be more disastrous for Soviet Union than Trotsky, so in all probability Soviet Union under Stalin would have been a nice place, probably resembling a Scandinavian social democracy if he could kept power for long enough time.