I wrote a (very surface level) comparison on this last year[1]. If you already have V8 in your environment, it's probably worth using V8, but if you just want to load a wasm interpreter into some Rust code, wasmtime is a much nicer interface to work with and more lightweight.
[1] https://paulbutler.org/2021/calling-webassembly-from-rust/
(nb. if I were to write this post today, it would be an omission not to mention the component model)