I've decided to switch to M&M.
After a long hard think about the options I decided:
1. I didn't want to go back to BA (I used to have BA Gold but became disenchanted with the rubbish levels of service and stupid cabin layout).
2. I thought about A3, US and OZ but decided against it as I'm not sure how stable their programmes are.
3. I considered TK but decided that it would end up being a headache to book award flights.
4. I decided against United and Air Canada as I don't want any obligation to use their planes.
5. So by default, M&M is the best fit for me. I get to stay with *A and I'm confident that they'll still be here when I want to make a redemption. The earn/burn rates are not the best and 100,000 to get to Senator is steep, but my thinking is it's the largest and safest programme out there and the LH/LX routes cover the places I need to visit in the next 2 years (India, China, US, Japan).
So, M&M it is...
Just got to work out what to do with the DC miles now as I want to avoid getting drawn in to the whole BA/Avios thing....