A sufficiently large balloon with enough payload capacity (and some method of data link back to its operators) would probably be more useful for SIGINT and rf s

A sufficiently large balloon with enough payload capacity (and some method of data link back to its operators) would probably be more useful for SIGINT and rf spectrum data gathering, assuming it has directional antennas aimed at whatever is directly underneath it. Same capability in a LEO satellite weighing 500kg+ might be very costly to launch.