Speaking for myself, I suggested big name rigid mountain bikes is for a number of reasons. First they are usually easy to find for not much money. Second, if components need to be replaced or fixed they tend to be easier to come by. Third, they tend to have beefy frames, stable geometry, and eyelets for racks and/or fenders.

The problem with some of the xmart bikes are not knowing who assembled them. Some parts are difficult to come by. Non quality parts are used.

Since your price range looks to be around $150 there are fewer choices. Most importantly get something that fits and you would enjoy riding.