"I find it IS better" is more of emphasizing a thing in comparisson with another thing. "I find it better" (casual) on the other hand has different meaning like when you want to agree on a certain thing: A: "how do you find your new office? ('find' here = assess/evaluate) B: I find it IS better than my former office. A: "how do you find your new office? is it okay? B: "yeah, I find it better" or: "I want to wear my blue jeans. I find it better for my long-hour travel.

Actually what Madam jura say is correct those sentence you posted can be use its only for you what you will use.

You can use either, but 'I find it is better' sounds more formal.eg I find that it is better to pay off the credit card before the due date.