2. Rondale Moore
If the Falcons are unwilling to spend much cap space at the position it would be wise to re-sign last season's trade acquisition. Rondale Moore joined the Falcons expecting to be the team's third receiver and offer the team some much needed speed. Moore struggled a bit in camp before suffering an injury that would rob him of the chance to win the third receiver role.
Even if the receiver hadn't won the role over Ray-Ray McCloud, the Falcons were unquestionably going to use his speed. Whether on gadget plays or simply as the 4th receiver the Falcons had every reason to work Moore into the lineup.
There is a much higher ceiling than what you gave up in Desmond Ridder. The quarterback was never taking the field again in an Atlanta uniform. Allow the receiver a chance to return on a cheap one-year deal and see if the fit still makes sense. It is the type of low-risk move that is more likely to happen considering the team's lack of cap space. It isn't as exciting as adding an established veteran receiver. Though there is an easy argument it could come with a higher ceiling.