If you are UK based, you need to be practical. Do you earn enough miles from flying alone to support your redemption goals? If you've got a family to fly, almost certainly not.
You therefore need a programme which allows you to earn in other way. This may mean one that has a UK credit card (United, M&M) or that allows Membership Rewards transfers. Lufty has been quite good in Germany with non-flying earning routes - it remains to be seen if they improve their UK efforts when DC is gone.
Remember that *A status matches are fairly frequent, although you often need to use a false address in another country to get them! I have had Star status, Silver or Gold, since 2005 entirely through status matches - although, of course *A Silver is no good for lounge access except when flying the airline which issues your card.
You also need to remember to compare the miles earning chart with the miles needed for status. 20k for Gold may sound low, but if you only earn 1.25x for J and nothing for low-price Y tickets (as a made-up example) then it may actually be tougher than getting status with an airline requiring 40k but giving 2x for J and 1x for cheapo Y.
Also worth remembering that some *A airlines give more than 1 years status. Asiana and M&M offer nearly 3 years of Gold status if you qualify at the right time of year, for eg - I think Thai does too.