I’m looking for a spacious, feature-loaded 7-seater for a family of six adults. My annual usage is about 10,000 km with a 40:60 city - interstate split. I’m choosing between the Mahindra XUV700 AXL and the Toyota Innova HyCross GX(O). I prefer to keep my vehicles for many years. Which would you recommend?

Both the Mahindra XUV700 AX7L and the Toyota Innova Hycross GX(O) are good SUVs, but quite different in character. 

The AXL variant of XUV700 is feature-rich and a performance-oriented SUV with strong petrol and diesel engines. 
The Innova Hycross GX(O) is the top-of-the-line non-hybrid or petrol-only variant, which is a practical and reliable option but lacks the tech and the wow-factor of the XUV700. 
Both SUVs are spacious, but the Hycross is also more comfortable than the XUV700 with a smoother ride and more room in all three rows. 
However, we feel for your annual running of only 10k a year, which is mainly on the highway, the diesel XUV AXL will be the best option as it offers strong performance, effortless cruising and despite being a diesel is quite refined. Plus, the AXL comes with ADAS features, which can be a lifesaver in high-speed situations on the highway.
You should wait for the Mahindra XUV 7X0, which is the updated XUV700 with extra features like a third screen front passenger, to be launched in early January 2026, before making your decision.