Yanmar makes many of the diesel engines used in Mahindra tractors. My independent tractor mechanic told me Yanmar was the very best diesel engine maker, calling them "bulletproof," if you take care of them.
Mahindra offers a 7-year warranty on the Power Train; this has been a standard Mahindra offering, for many years. That spoke volumes to me, before my purchase of a used 20 HP Mahindra. Have owned it for several years now. Love it, and I have driven it hard, more than I care to admit, even to myself.
Mahindra is the top selling brand, by sales volume of tractor units, in the world; they have been in that position, for a number of years. This, too, spoke volumes to me, and it still does. It is hard to argue with a long-running, success story, like Mahindra.
I had never heard of Mahindra before I found mine. I've learned a lot about them since my purchase, and I am still glad I bought it! The more I learn about Mahindra, the happier I am with my purchase, but that is me. Your situation is unique, like mine.
Having said that, I believe nearly all brands of tractors are really good, durable, long-lasting machines, when taken proper care of. Cheers!