Independent Ukraine
How much this matters depends partly on how much of what is now the Ukraine remains independent and how well governed it is. Any significant independent Ukraine cuts into the Soviet ability to feed the USSR without imports or more investment in farming. A Ukraine that extends east to the area around Kharkov cuts into Soviet coal and iron production.
Other impacts: If it extends far enough east, an independent Ukraine would shield Wrangel's White Russian army from land-based attack by the Soviets. Any significant independent Ukraine would also alter the balance of power within the Soviet Union quite a bit. The Ukraine was the most heavily populated Soviet Socialist Republic other than the Russian SSR. That means that the rump USSR would be even more heavily Russian dominated than the historic version. However, there would be a smaller proportion of Slavs to non-Slavs, especially Moslems than there was historically.
Bottom line there: A considerably less powerful Soviet Union with less pretence of being a multi-national society.
From the Polish standpoint, having an independent Ukraine would be a mixed blessing. On the one hand, it would give them a valuable buffer against the Soviets if the Soviets became strong again. On the other hand, interwar Poland contained large chunks of territory that were Ukrainian-speaking and did not want to be part of Poland.
As a matter of fact, the formerly Austrian part of what is now the Ukraine fought a bitter war with the Poles shortly after World War I ended, and around 100,000 men from the defeated army of the "Western Ukrainian People's Republic" went into exile in the then still independent Eastern Ukraine rather than live under Polish rule. If the Ukraine became strong it would encourage Ukrainain nationalists in Polish-held territories to try to become part of it, just by being there. The Poles had enough problems controlling the Ukrainian-speaking areas of interwar Poland as it was, with a low-level rebellion continuing through most of the interwar years.
How would an independent Ukraine shape up? Based on what I know of Ukrainian governance in the brief period they were independent, not so well. The part of the Ukraine that had been controlled by Russia before World War I was largely agricultural, with a lot of poor, poorly educated peasants and very few people with much experience governing a country or even a town. Of the educated minority, many were close enough to the Bolsheviks that many of them joined the party in the early to mid 1920s, and were purged fo nationalist tendencies in the late 1920s. Then there was Mahkno and his anarchists, who controlled (or at least kept anyone else from controlling) large parts of the southern Ukraine. I'm guessing that the Ukraine would be poor, unstable and militarily vulnerable until able leaders emerged and gained experience. I woud guess that it would take ten years before that happened, assuming that the Soviets stayed out long enough for it to happen.
Unfortunately for the Ukrainians, they simply didn't have many people experienced in making things work because the Russians had worked to prevent Ukrainians from acquiring those kinds of skills. By contrast, the Poles had a class of people from the formely Austrian part of the Ukraine with experience running at least the local government of the primarily Polish areas, and some Poles had long been part of the Austria-Hungarian government, so the Poles had some experience to draw on.
I don't know exactly where this leads, and it may be more info than you wanted, but hopefully it gives you some ideas one where this could go.