Hi 👋🏻 the sentence is okay. However, I would say ‘I don’t know what is better; but maybe neither do you?’ Or ‘I don’t know what is better, and possibly neither do you?’ More as a question than a statement.

It is a perfectly fine sentence. You may have wanted to phrase it, "I don't know which is better, but I guess neither do you. "

Hi, You have a comma splice error. This happens when you join two sentences with a comma. Two fixes to this problem are changing the comma to a period or a semi-colon A semi-colon is okay when the second sentence directly relates to the first; in your case, it does. Cheers

It sounds fine ; if writing in any formal way, don’t use ‘texting’ abbreviations like ‘u’.