While that is the intended use of this product, we would need more information to comment on specific applications/projects.
It would be up to the Designer to specify the appropriate connector for the specific application. We do not have a specific product designed for chair leg attachment. It is not clear how it is intended to be attached in this application. Please see the L angle product page for the allowable loads, load direction, etc.: https://www.strongtie.com/reinforcingandskewableangles_anglesandplates/l_angle/p/l-angle. Also, please feel free to contact our Engineering Support Department (800/999-5099) to discuss further. Thank you!
The L Angles are only 16 gauge and are not designed for this application; please see the 12 gauge TA Staircase Angles. Thank you!
The ML was not designed/rated for loads in the direction that a stair tread would put on it. Please see the TA Staircase Angle for a product intended for this application. Thank you!
It would depend on the application and which L vs. framing angles you are referring to. Comparing the F1 loads of the L70 listed here to the A35, the L70 has a higher capacity for wind/seismic conditions, but he A35 has a higher capacity for floor or roof conditions. Also, depending on the size of the members you are joining, the ML26Z may be an optoin. It installs with SDS screws and has a higher capacity than both the L70 and A35. Ultimately it would be up to the Designer/Engineer of Record to specify the appropriate connector based on framing layout, demand loads, local building codes, etc. Thank you!