I'd have to look back at Francos use of the death penalty and extra judicial killing to offer much of a comment on the equivalence. My memory is a bit hazy but I recall thinking Franco was significantly more zealous and prone to summary executions but yip I'd be broadly content to agree that both left a lot to be desired in that context. The context is important to providing a full picture however - Franco overthrew a democratic govt and implemented the 'white terror' see
LINK while Castro overthrew a despotic mafia state that was killing 10's of thousands of Cubans and executed (mainly) its former henchmen.
At the end of the Spanish Civil War the executions of the “enemies of the state” continued (some 50,000 people),[175][176] including the extrajudicial (death squad) executions of members of the Spanish maquis (anti–Francoist guerrillas) and their supporters (los enlaces, “the links”);Thousands of men and women were imprisoned after the civil war in Francoist concentration camps, approximately 367,000 to 500,000 prisoners in 50 camps or prisons.
I dont think there's an equivalence with Cuba there?