Hitler would famously tell Mussolini, "I prefer to have three or four of my own teeth pulled out than to speak to that man again!" It is subject to historical debate whether Franco overplayed his hand by demanding too much from Hitler for Spanish entry into the war, or if he deliberately stymied the German dictator by setting the price for his alliance unrealistically high, knowing that Hitler would refuse his demands and thus save Spain from entering another devastating war.
Suppose Franco had lost and the Republicans had won? The era leading up to WW-II as they consolidated their power would have been even bloodier than it was under Franco--almost as bloody as the civil war itself--since the Soviets were determined to control the regime; and the regime was already extremely brutal.
Not too long after the fall of France, Germany would have found some good reason to overrun Spain. A cursory search(*) didn't show me any special National Socialist attitudes towards Spanish heritage, but given the admixture of Moorish ancestors in Spain I'd bet they'd have come up with some reasons to claim radical inferiority for the Spanish once the Germans took over the place. (The whole course of the war would have been very different if the Germans had controlled access to the Mediterranean. Germans or Soviets--which would have won?)
Preston, though admitting that corruption in Spain pre-dated Franco, says Franco's regime was corrupt and "In general, the idea that public service exists for private benefit is one of the principal legacies of his regime." Umm. No. That's pretty much the description of political corruption; as it was before, during, and after Franco in Spain and in Chicago.
Sometimes there aren't any good guys in view; this seems like one of those cases. The Spanish could have had it a lot worse, though.
(*)Forgive me for not delving deeply into that kind of stuff.