All of the above.
When Dresden casts Fuego as a Rote (which requires the control bonus from his rod), it's automatically controlled successfully. While he could theoretically cast the same spell as a non-Rote, even with his rod he has almost a coin-flip chance of suffering for doing so, and without his rod his chances of failing control are significantly higher. Dresden can actually invoke the "Quick to Anger" part of that aspect as a bonus to his fire spells (magic can feed off strong emotions, including anger) which ironically
improves his control. Of course, the GM could also argue that such emotions could lead to a loss of control, opening up the possibility of a compel. Given that Dresden is perpetually short on Fate points and that his GM is Jim Butcher who
loves doing evil things to him, which situation is more likely?
So yes, I think Dresden prefers casting Fuego as a nice, safe, Rote,
because he knows his GM hates him and will make him suffer otherwise!