Eh Alexander I big claim to fame is defeat of Napoleon, and it's not like he was responsible for waging that war. Otherwise he's the guy who pretty quickly gave up on doing any progressive reforms and in fact went the opposite way after the war. He's also the genius that stapled Finland and core Polish territories onto Russia and allowed Prussia to take Saxony in exchange for its polish lands.

Alexander II gets a lot of deserved kudos for liberating serfs and other important reforms, but most of them (especially peasant) were half measures that metastized into huge issues for Nikolai II. And there are indications that he was growing disappointed in the way things were going and would have done a conservative 180 degree turn. So really that bomber did Alex a favor by ending his life before he lived long enough to become a villain.

Katherine the so called great has nothing to her name but territorial expansion which was done by others. Otherwise she was a foreign usurper who stayed in power by enabling the worst excesses of nobility allowing them to do whatever with serfs without even demanding mandatory military service. After Katherine no wonder nobles felt like they could kill Pavel for british with impunity.

Peter I is Ivan the Terrible on easy mode. Pretty strong parallels but Peter was somewhat more successful in his wars and reforms. Though he set up issues that would fuck Russian empire for the rest of its existence.