"As needed - open to offers" is extremely vague, and arguably self-contradictory. Strictly speaking, "as needed" implies that you're available 24/7. But "open to offers" seems to be saying "tell me when you want me and I'll tell you if I'm available".
"More than 30 hrs/week" is also unclear. Does it mean that you're available to Upwork clients for 30+ hours a week in total? Or does it mean that you currently have 30+ hours per week available in addition to your existing Upwork commitments?
To me, "More than 30 hrs/week" gives the impression of greater availability. If you want to say that you have plenty of free time available for new clients, I would probably pick that one. But, given the vagueness of both options, I doubt it makes much difference.
That said, I'm assuming that the only effect is on clients, based on how they interpret this text. I suppose it's possible (though it seems unlikely to me) that it also has some effect on Upwork's search algorithm. (As I can see, there isn't a search filter for this parameter.)