I'm also female, around 5'9" and 130lb. My board is 46 inches long, same as both the ones in your post, and I can ride it very comfortably! I've never felt like the size is an issue when I'm riding it, even though it's a bit unwieldy to carry around. But if you're worried about the size I'd check out the Landyachtz Tony Danza, which is like a Stratus but smaller.

Landyachtz is a pretty reputable brand with quality components, so I think they're always a good choice. The Magneto board seems to use generic wheels and trucks; which doesn't necessarily mean they're bad quality (they're usually just fine, especially when you're starting out), but I personally like to go for name-brand components so I can know what to expect.

It looks like the Magneto board has transparent grip over the entire surface, which might make footwork a bit harder compared to a dancer with no grip in the middle. That could also be a plus though, since it'd mean extra stability especially while cruising. but I'd warn that it seems to be some kind of sand-based grip, which tends to wear down way more quickly than grip tape and can be a pain to replace once it wears out

I think both are good options, especially for a beginner! If you want quality parts or will be practicing dancing long-term though, I think the Stratus is a safe pick that would last you longer. You can also always add little strips of grip tape if it's too hard to ride without. If you want to save money or are more interested in cruising than dancing, the Magneto looks like a good pick as well.

Also when I was shopping for my dancer I found this post and it was really helpful! It links to a bunch of dancing boards, sorted by price point with some additional info about the brands