Some kinds of sensor must be read on a very strict schedule or else the information received therefrom will be erroneous, either because the read has to have a certain timing relationship with some other event (e.g. one is measuring light reflected from illuminating lamp which is only for 100us every 10ms), or because readings encapsulate implied timing information (e.g. if one is trying to sample audio at 44100Khz, each reading should encapsulate the fact that it was taken 22.6757 microseconds after the previous one; simply taking 44,100 readings at arbitrary times throughout a one-second interval is not equivalent!). Other kinds of sensor may be read at one's leisure.
If you are dealing with the former type of sensor, you should either have a very-high-priority scheduled task to do the reading, or else do it within a timer interrupt that's dispatched directly rather than through the OS. Arrange things so that unless the application gets so far behind that data loss will be unavoidable, the sensor-reading code will always have someplace to put its data. If you have multiple sensors that need to interact, it's often good to handle them all within the same timer interrupt when practical. If everything can be handled by e.g. a 10Khz sensor-handling interrupt, using one fixed-rate interrupt for everything is often much simpler than trying to deal with changing interrupt rates, even if oftentimes the only thing the interrupt will do is decrement a "how many more ticks until I do something interesting" counter.
Sometimes having different tasks for different sensors can be a good approach, but if any sensors share resources (such as ADC channels) it can be very difficult to ensure that there are never any timing conflicts. For example, if e.g. one has one sensor that needs to be read at a strict 5KHz rate and another that needs to be read at a very strict 2Khz rate, and both sensors use the same ADC, it may be most helpful to have a 20Khz interrupt and arrange things so that each interrupt captures the previously requested reading, requests a new reading, both, or neither, and the two sensors will stagger their readings so they never need to have requests pending simultaneously. If the two sensors were handled by separate tasks, ensuring that no sensor will want to use the ADC when the other sensor is using it may be more difficult.