Which class should an armored Wizard multi-class with, and in what order?

For a Wizard who plans to be in battle, what factors should be considered when deciding between taking a level or two of Fighter or of Cleric, and when?

Fighter 1 would give the heavy armor proficiency and the proficiency on CON saves, and seems like a good way to go.

Cleric 1 would also give heavy armor proficiency, proficiency on WIS saves, and progresses the spell slots. L1 Cleric healing (and other) spells could be cast from higher level slots making this a nice “bonus” set of spells to have available.

I realize there are trade-offs and it’s not a factual question to ask which is better, but are there factors I’m failing to take into consideration?

Is there an argument for taking the first level of Wizard first? It seems like you lose out on more than you gain that way.

(If it matters, we’ll start playing at Level 3)