+2 for practicing good epistemology. It's in bad form to ask for arguments to support a conclusion you already support or find yourself defending; it's better to aggressively try and attack your own preconceived notions and find flaws in things you believe, then you know you can more readily defend what remains because you should be familiar with what one might say to attack it. In the case of Ukraine, a lot of the arguments in support of Ukraine can be thought terminating cliches:

• Russia attacked Ukraine, initiating a brutal invasion that's killing a lot of people. That's bad and supporting this makes you a bad person. (This is a reductive and moralistic argument: critics of Ukraine aren't asking for the war to be expanded or extended, so why should the moral weight of the war itself weigh on their shoulders, instead of the consequences of withdrawing support from their respective countries?)
• Ukraine is a democracy while Russia is a dictatorship. (this one is also reductive. Ukraine and Russia both have enough corruption and flaws in their democratic regimes that they may be accused of not meeting some standard or another, since the line delineating what is or isn't a democracy is very arbitrary. Furthermore, they're both capitalist countries.)
• Russia is committing genocide. (While I could say that this falls for the same errors as the first statement, IMO if Russia was actually committing genocide it would be grave enough to warrant international support for the defending parties. But this is not the case, and it depends on the accuser to present evidence that Russia is actually deliberately murdering civilians in a genocidal manner)
• Russia is homophobic/racist/reactionary in some way (these charges are probably correct, but immaterial to the conflict since there is no notable way in which Ukraine is less socially conservative than Russia)
• Supporting Ukraine strengthens democracy worldwide (NATO's involvement in Libya and Yugoslavia show this isn't the case at all, and the opposite is true)

I might be missing some, but I think those are some of the ones you'll hear often. I don't know of any much stronger arguments, though! It frustrates me because sometimes, in a debate about capitalism, imperialism, etc. there will be some more plausible arguments from the right wing side than simple thought terminating cliches. But in this case most of the conversation marches to the beat of simplistic propaganda narratives.