i have converted form MPO Diamond to AA EXPLT.
so for my one experience, AA EXPLT is more attractive. you can find comparison with a search, but there are the highlights
1. 3x mile bonus, VIPOW
2. good CX awards ex-N.A.
3. well treated by CX
4. the full fare upgrade
5. AADV is still better than MPO as a program and more flexible (MPO is good in service, but not flexible enough)
downsides
1. many CX disc econ fares are not qualified (but if u have a canadian address, u can get the miles)
2. no lounge access in FL/AC fro domestic travel
3. guaranteed seat on CX
4. thin coverage of AA/AADV is u r based in asia