Part of me finds it perplexing to imagine a dream job. Retrospectively, I wonder how frequent these types of discussions were amongst our ancestors. Were those bound to one guild dreaming of being bound to a different guild? How integral was a career to a family's identity? Would seeking a different career equate to denouncing one's familial pride? Moreover, would all Ancient Romans have wished to be managers or governors? I've read manual labor (including professional craft) was considered to be lowly. I'd have to research this.
Anyway, my personality would be split on this one. If not a career in coding (it's currently the middle ground), I'd go for a film soundtrack composer like Hans Zimmer or a vet at an animal sanctuary or zoo.