what contractor will prefer
 

what contractor will prefer?
i have a 7 feet wide wall footing. wall is 18 inch wide and footing is 18 inch deep (thick). it has rebars #5 @ 12 " c/c top & bottom e.w (each way).
i checked i do not need to bend rebars at ends to attain development length. most likely will contractor will go with plastic chairs or will like to bend it at ends
to give support to top mesh from bottom mesh?

you won't find chairs tall enough for your top bars. it's easier for the contractor to use bent bars and ties to hold the rebar cage together.
bottom mat will likely be supported on concrete bricks.