Mr Optimistic,
1.3M baht is the bottom of the range for established brands for both car based SUVs like CR-V and CX-5 and pick-up based SUVs like Everest, Pajero Sport, Fortuner. There are cheaper versions of the Isuzu MU-X from 1.1M. Base models can be pretty bare so best to look at the specific models in person. In the past, the pick-up based models have depreciated more slowly and been easier to maintain in the long term / high mileages.
The cheaper options for smaller SUVs like the Corolla Cross, Honda HR-V, or MPV style cars like Honda BRV and Mitsu Expander etc. can be a bit small for 5 large passengers.
The less established models like MG ZH and Haval H6, as noted above, may work if you have no particular brand preference.