While M&M would give you 200% miles (both elite qualifying and redemption) for full fare business class flights (less or none for discounted business so check your fares carefully) it will be more challenging to earn STARGold with that program versus AC Altitude. Assuming 8K of base miles for each of your (minimum 6) TATLs you'd earn 48K+25% bonus for business class if you do these returns with in a calendar year. That would get you AC's 50K Altitude and full STARGold benefits.

If all your flights qualified in M&M, you'd earn about 96K or just short of the 100K you'd need as a non-European resident member of M&M for Senator status and STARGold. M&M has no intermediate tiers between Frequent Flyer (at 35K) and Senator. However, if you are only flying LH-affiliated airlines, and are in business, you'd not need many of the STARGold benefits, so STARSilver, plus the extra benefits LH gives when flying its airlines, should be enough.

Not knowing where your domestic flights would be, it's hard to know how many base miles to assign, but one could assume these would put you over the top for M&M, and likely past 100K with AC Altitude, giving you top tier in either program.

There are major issues with redemption of miles in both programs, and particularly the high surcharges on most STAR partners' award tickets. In this regard, you are better off opening a UA Mileage Plus account and put your flights into this STAR program. Since you are flying premium revenue fares, elite benefits are not going to be of much interest to you. However, by putting your flights into MP when it comes time to redeem miles for flights, you will save hundreds of dollars on each award ticket even when booking LH or AC, two of the biggest offenders. (For some reason, MP does not add on these surcharges, so the same flights on an LH TATL might cost $350-$500 redeeming with M&M or AC/AE, it would only cost about $50-$75 using MP miles.

You should also be able to earn at least 75K Platinum status in MP based on your TATLs, and full 1K based on passing 100K of base qualifying miles, which will give you a bonus of 100% more redeemable mileage for your flights on most STAR carriers. (This is stepped based on hitting various elite tiers over the year, so at 25KSilver you'd get 25% bonus miles, then at 50KGold it would be 50%, and at 75KPlatinum 75%. You actually will earn the status once you pass each threshold, and although you won't have your previously earned elite tier bonus miles increased, the new ones will be calculated at the higher level. You'd also have STARGold status on you hit 50KGold to use when flying other alliance partners. However, at 1K top tier UA/MP elite you will get 6 Global Upgrades which can be converted into paper vouchers to use to upgrade LH flights from business to First Class...or use with UA overseas flights for similar upgrading (from mid-level economy to business, or business to first). You will also earn credits to upgrade NAmerican UA flights, as well as be eligible for no-cost upgrades from any economy fare to first.

So to me, your decision must be made on how you plan to use your miles, not on the FF program benefits or even attaining STARGold status. If you don't mind paying several hundred dollars more for awards, then since you're flying LH airlines, go for M&M. Otherwise, go for MP. Stay away from AC Altitude/AE unless you plan to fly domestic within Canada and want to take advantage of upgrades, but again you may also be buying business class on these flights so it wouldn't matter.