I'd say Valeria is smarter, but Loki would probably win in a scheming prep war, as some of the resources he has access to are going to be things Val will have a hard time dealing with.
Not that it wouldn't be the same, Val's tech would cause Loki problems, I just think she'd have a harder time overcoming Loki's magic and general scheming than he would hers.
I think Valeria would take it if her statement of being her fathers superior proves true. That said she also lacks the experience and I'm not too sure how she'd handle magic which she has relatively little experience with compounded by her overall lack of experience. I'll give Valeria the benefit of the doubt, more on speculation than anything definitive.
However feats based/concrete evidence I'll give Kid Loki the big thumbs up as he is an absolute champ of dickery in my book.
they both about the same age appearance-wise. Don't see why this wouldnt work. Up until Franklin goes into overprotective brother mode after hearing about this. Doesn't end well for Loki. So Valeria insta-win .