Canada has the option of Aeromexico for South America and Central America with several cities such as Toronto and Montreal over 2000 miles which increases to 24 XPs per segment.
Delta is your classic friend in the United States, but don’t focus on segments as even a JFK-LAX would only earn 6 XPs in Business Class!
Here you have two major options: you can use Aeromexico which will connect and add segments via Mexico City especially for connections to the US with two international flights or if flying to Canada you can seek to fly with Delta and have a connection in the US.
The negative side of Delta is that their internal flights, the same as in the case of Aeromexico, do not credit very nicely and only give you 6 XPs per segment in business class.
Aerolíneas Argentinas is usually one of the only options for intra Argentina flights for those that accumulate alliance miles. They offer a premium economy product which at times has a 2-2 seating see these trip reports but do not credit very well to either Delta or FlyingBlue.
There is also an Air Europa flight between Asuncion, Paraguay and Cordoba, Argentina
The best opportunity for flyers based in South America is to use Aeromexico which traditionally has very cheap fares from South America to Europe the best example is Sao Paulo to Madrid which at times can be found for less than $1,200
Some of the best opportunities are via Kenya Airways which in addition to being the only SkyTeam airline that is based in Africa for a sense of variety of opportunities to connect via their hub in Nairobi and have multiple stops which add XPs.
Either Johannesburg or Cape Town to different locations such as Zambia, Mauritius as well as Eastern Africa and these provide good opportunities to accumulate at least 60 XPs
Air France flights from Algeria to Tunisia or Morocco to Tunisia or vice versa as these allow you to connect in Paris and accumulate additional XPs, especially with the current promo of 50% more till June 30th.
Middle East / Levant
The star is Tel Aviv which besides being the largest commercial City in the region also has several flights a day from Paris with wide-body planes. KLM flights are narrow-bodies with the Euro business cabin which can be brutal.
MEA is another partner but due to the instability in Lebanon has not traditionally offered good connecting flights focusing very much on a VFR format or visiting family and relatives