Seriously...

I mean... Opinions are just that. Opinions.

Surtr is a mobile game villian he isn't suppose to be good. He is more like a force of nature then a person. Sephiran is more a villian then Zelgius is,Zelgius is only really an enemy to Ike when all is said and done.

Walhart and Aversa are good villians. Walhart is popular for the way he is portrayed as a conquerer to Chrom's King,and for the fact that he opposes the Grimleal. Aversa,despite her outfit,is a good villian because she outsmart Robin when they try to rescue Emmeryn,then she tricks Exodus into starting a war that drags Chrom's group into it. She also has a sad backstory,like Zelgous,in that her village was massacred and that the man who destroyed her village brainwashed her into servitude.

But most FE villians are one dimensional anyway,like Garhnef,Ashnard,Surtr,Garon.

Why is Sutr shit. He's Thanos.

From what I've played FE plots are fairly generic overall, maybe a slight twist here and there, but overall nothing too shocking (note this doesn't necessarily make any of them bad, just mostly predictable).

Well, I think that awakening had fine villains, if you ignore Validar.
Fates had shit villains, though you had the sibling of the opposing family as antagonists. The hosidan siblings and Leo were quite good antagonist. Xander wasn't though.. His character just did what the plot needed him to do.

You could make a case that Echoes is after RD, since the villains didn't have any character in FE2.
So then we can add Berkut and Rudolf to the list.

Surtr is burning in Hel-l with Lang.