What if, as he planned to do originally, Franco had been able to join the Spanish Navy? Without his experiences in the Rif War he is taken out as a likely leader of a Nationalist force. Will the Civil War still happen? If so who would lead the Nationalist side?
Well he was not sure to join the rebellion anyway, and was far from the leadership, until a lot of bizarre accidents, executions and simply luck landed him in the post ...
Butterflying the US-Spanish war would produce a Franco in the Navy ... but of course the massive butterflies could make the SCW a non issue ... ( a bit more spending in the Navy at the beginning of the 20th century is also possible, but more difficult )
For choosing another leadership for the rebels you can simply kill him or seriously wound him in Morocco ... thats easier.
Mola and Sanjurjo are the most probable leaders Queipo de Llano is more difficult but not impossible ...