TX and FL are "important" only in the sense that they're big states that solidly lean Republican, so the GOP losing there would be very detrimental to their ability to develop policy at the state level (as other posters have alluded to.) However, there's no realistic chance Republicans lose either state this year.
What happens in the AZ/KS/NV/WI quartet seems most important in developing a narrative about who "won" the midterms, so I'd rank those four as being of equal importance to the GOP.
Lake is so insane she doesn't belong in the category. I think MI is more important. Dixon is not a good candidate but she's not bad enough to lose in a year like this.