Majority of my flights are from India to Europe, North America and now Brazil. I am a Premium Exec member with 80,000 miles with United this year. I have qualified for Star Gold 4 years in a row now, but I am planning on switching to Miles and More with Lufthansa. Reason being that I could never use my United miles to upgrade on Lufthansa since the booking class it had to be booked in was very expensive. It is important for me to have Star Gold status with the amount of waiting I do around the world, lounges would be nice. I do realize that Air Canada can make me Gold in 35000, so I was thinking about splitting it. In which case I would first achieve the Gold status and then continue earning the rest of the miles with Lufthansa. The other choice was to try and aim for the 100,000 of Lufthansa. Which option is better? Also, in United the 50k needs to be accumulated with Star Alliance partners only, is this the same case for 100,000 of Lufthansa. Can I earn on Air India who is a Lufthansa partner and that will work towards my Senator?

Welcome to FlyerTalk!!

Keep in mind on the Air Canada option that unless you fly some actual Air Canada flights you will not earn status with them.

Beyond that, you'll probably want to check out the Miles + More forum for some more details about that program.

There are 2 types of miles: status miles which define your membership status, and destination miles which can be spent on award bookings and upgrades.

When flying LX a route earns, say 500 miles, you earn 500 status miles and 500 destination miles. When flying on non *A partner airlines, like on your example AI, you will earn on LH MM only destination miles. So, flying AI will not help you to achieve SEN (thus *A G).
No *A will let you earn status by flying non- *A partners.

Flying 80,000 miles on LH or *A partners will only earn you Frequent Traveller (*S) status. You need 100,000 miles to reach Senator (*G) on M&M. However, your status is good for two years (compared to only one year with M+) and you get 25% bonus redeemable and equity miles after reaching Frequent Traveller. If you reach silver the first year, then you only need to fly 80,000 to reach Senator the following years. The other disadvantage of M&M is that you only receive two upgrades for hitting Senator (compared to 6 SWU's for M+). Having said all that, given your travel patterns I still think it might be worth switching to M&M. You can reach your most common destinations by connecting in FRA or MUC, and LH will treat a Senator better than a UA *G.

This would actually the only reason for the OP to switch to MM.

Do you have an option to reach 100,000 EQM with UA? If so, then you will get 6 SWU per year which can be used on LH flights at reasonable booking classes (fare bais codes).

According to me the booking classes do not change even if you have 1k. It still remains Y or B, which are so expensive that I might as well pay for Business class.

The Y/B fares are required for miles based upgrades, not SWU upgrades. The use of UA SUW's on LH is not limited to only Y/B fare codes; they can be used on several lower fare booking codes to upgrade to C as well as for upgrades to F from J/C/D/Z. There is a long thread in the UA forum on the use of SWU's.