Regarding Poland, no, the Soviets were not worse. The Nazis subjected the Polish to the holocaust, and was committed to exterminating millions of Poles. One historian saying "in many ways, the soviets were worse" doesn't even mean the soviets were worse in total, yet that's the implication you bring. Historical evidence backs up that the Nazi colonization of Poland was a prototype for the Nazi colonization of the Soviets.

As for Stalin and preparation for Barbarossa, again, reports conflicted. The Soviets knew that the Nazis were going to eventually invade, which is why Stalin had the Red Army prepare for German invasion. It wasn't that Stalin didn't mobilize the Red Army, it's that Stalin refused to muster forces on the border, which was exactly what the Nazis wanted. The Nazis wanted to quickly route the Red Army and march straight to Moscow relatively unopposed, instead they ran through largely empty, wide-open land quickly, before running into extreme resistance.

If you don't trust Goebbels, there's plenty of other testemonies from Nazi officials, such as General Fedor von Bock in late July:

The enemy seeks to recapture Smolensk at all costs and is constantly sending in new forces. The theory expressed by some that the enemy acts without plans is not reflected in the facts […]. We’ve verified that the Russians have brought up across the front a new and compact deployment of forces. In many areas they seek to go on the offensive. It’s surprising for an adversary which suffered so many blows; they must possess an unbelievable amount of resources, in fact our troops still lament the power of the enemy artillery.

Here's an excerpt from Domenico Losurdo's book on Stalin:

Long read as an example of political-military ignorance or even blind trust in the Third Reich, the extremely cautious approach taken by Stalin in the weeks leading up to the outbreak of hostilities now appears in an entirely different light: “The relatively open concentration of Wehrmacht forces along the Soviet border, the violations of Soviet airspace and numerous other provocations had only a single purpose: to draw the main forces of the Red Army as close to the border as possible. Hitler wanted to win the war in one gigantic battle.” Even valiant generals were enticed by this trap. Expecting an onslaught, they insisted on a massive relocation of troops toward the border. However, “Stalin categorically rejected this demand, insisting on the need to maintain large-scale reserves at a considerable distance from any conceivable front line.” After the war, studying the material left behind by the German architects of Operation Barbarossa, marshall Georgy K. Zhukov recognized the correctness of the line pursued by Stalin: “Hitler’s command was counting on us bringing our main forces up to the border with the intention of surrounding and destroying them.”

Now, you may say that Zhukov was simply trying to play the political line. However, it's abundantly clear that this is in fact exactly how it played out. The rapid conquest of largely open land was met with a rapid counteroffensive that placed the Nazis in a dreadful stalemate, and eventually a legendary counterattack. Had Stalin listened to his generals, it's likely they would have played into the Nazi's plans.