I'd try to get both. Though if I had to, I'd probably get a female first.

Females are the key to the supers, you can't make supers without females. I'd get a female and start getting her up to size, then you could buy a male the following year and they'd both be breeding size at the same time.

Most say get a male first, I would agree if you were getting a super form of whatever male morph. But lets say you just get a co-dom and breed him to a normal female, you'll have a 50/50 shot of getting said morph. But odds can be a pain, you might get 50/50 morphs, but sex ratios are goofed up, or good sex ratios but bad morph results. Even if you got a female in your first cross, you're still another few years from making a super.

And if I bought a female the same time you bought your male, I'm going to be making supers sooner than you.

Co-dom females are way underrated IMO, can't have enough of them. It's easy to come by breeding size males, or get male hatchlings to breeding size quickly. Not so much with females.