You would be well pleased with either unit I think. The Max25 is built like a regular compact tractor, the BX is built as a SCUT. What is a SCUT? That is open to debate, but my current thought is that a SCUT will have a ladder frame with the components bolted onto it, like a serious riding lawn mower on steroids. Generally they have a transaxle in the back with a plastic cooling fan. Generally they have closer spacing on the 3-point, they will use Category 0 spacing with Category 1 pin sizes. A CUT (B-series in Kubota) will be built like a conventional tractor, just like a 50HP farm tractor, but smaller and will have standard Cat 1 pins and spacing. If they have a hydro, they have an oil cooler out by the radiator instead of a fan underneath.
A SCUT is lighter and probably a better mowing tractor. I think a CUT, like a B-series Kubota or a Max22/25 would in theory be a little more robust in the long term, heavier, a little stronger, designed for a higher duty cycle. That being said, folks that own the BX's seem universally happy with them, so obviously that sort of design is more than adequate for most uses. The eMax Mahindra is more along the lines of the BX Kubota, the Max Mahindra is more like a B series.
My favorite little tractor is the Max25. It has the same engine as the Max28 and the 3016, just rated at a lower RPM. Big engine, running slowly. Conventional structure for the drivetrain, and it is backhoe ready and comes with the three-point arms standard, heavy drawbar (for a little tractor anyway) and a 5 year warranty standard. We market the Max25 as a SCUT since it is physically nearly the same size and has a very similar turning radius, etc. You might argue that Mahindra has tried riding both sides of the fence on whether a Max is a SCUT or a CUT and I suppose that may be true.
I think the Kubota fans will say that the BX is the way to go since they own one and like what they own. The BX is the segment leader in sales, and that does not happen without happy customers. I'll agree they are good machines, so let me make it clear that I am not saying otherwise. I am though, making a distinction between the basic tractor structures. That may or may not matter to many folks. For me, if I can have a conventional tractor in a small size with a big engine turning low rpms, I would favor that.