"Raději" is a comparative form.

Positive good = rád

Comparative better = raději

Superlative best = nejraději

With "líbí se ti" you have to use "víc" instead of "lepší".

So it should be "Co se ti líbí víc?", literally "What do you like more?"

Can't say any specific rules, but do not try to invent unusual word orders unless you have specific reason for that. We often accept many, really a lot, of forms and word orders, but more often then not, most of them change the meaning somewhat by strongly emphasizing a specific word.

So do not invent word orders without any reasons, it is much better to stay with the basic SVO order. That it is not so simple with adverbs, I agree. Still, just use the same simple order English uses as well for this sentence unless the Czech adverb needs some other placement.

It's either "ty máš" or "vy máte" but not a mix of the two