Hi all,
I'm currently on a Star Alliance FFP, and is in the market for an OW plan. The answers to the sticky questions are as follows:

(1) What is most important to you in a FFP?
(upgrades on travel, priority services when flying the airline, extra baggage allowance, good award redemption rates, better award access, free - discounted lounge access, etc.)
Reply: Good redemption rates.
(2) How many miles do you usually fly each year & in what class? How many flights/sectors?
(<25000, 25000-50000, >50000 miles - <25, 25-50, >50 flights?)
Reply: I would say 25k-50k--however I was talking about the 2010s, and may not return to that level until 2028 at least--we are going to have a baby, and we don't think bringing a baby to a Transpacific flight is a good idea.
(3) What types of fares do you usually buy?
(First, Business, Premium economy, Economy, cheapest)
Reply: Economy to Premium Economy.
(4) Can you choose your airlines and/or class of service? Do you travel for work and/or pleasure?
Reply: Pleasure, so I have much freedom in choosing airlines. My consideration here has more to do with avoiding entering the US through LAX.
(5) Which routes and airlines do you fly most often?
(US Domestic, Transpacific, Kangaroo, in Asia etc)
Reply: Transpacific. I was born in HK and still have significant associations there (as well as the Pearl River Delta region), while my wife is a Japanophile. So I expect us to visit East Asia more than within the US.
(6) What is your home airport?
(SFO, SCL, London LHR, HKG, Singapore SIN etc.)
Reply: SAN (San Diego).
(7) Do you have FFP status of any kind in OW or other airline? What is it? Do you have any miles banked in a FFP?
(AA Executive Platinum, QF Gold, UA 1K, LAN Comodoro, etc)
Reply: I currently have about 130k on UA's plan and plan to redeem it for our final honeymoon this year, as well as downgrading the branded card to free-tier in the next anniversary. I also have 11k on Alaska/Hawaiian Atmos.
(8) Preferred Airlines? Most common Airlines flown on?
Reply: I'm impartial to Alaska, Cathay Pacific, and Japan Airlines. Miles-wise, it's probably JA, since we prefer their SAN-NRT flight.

Also note that we may consider moving back to East Asia in the future (I mean closer to 2030 than now), so that might be a consideration.