I know this depends on the story, but I'd still like to hear your opinion: is there an editorial (or agential) preference for narrative point of view or tense?
My WIP is literary fiction, a first-person retrospective of the layers of mental illness that have influenced the narrator's (a ninety-year-old woman) life and family over generations. The first person POV feels powerful, but I find myself slipping back and forth between past and present tense. (That is, either she is describing what happened, or she is in it as it happens). I have to pick one, but neither one seems obviously best yet, and I'm twenty-thousand words into the story. I'm just wondering if there might be a preference further down the editorial/publication line.
I'm sure individual editors have preferences but that's the wrong question here.
The question is (and always should be) what's right for your story?
And it sounds like you may have one of those rule-breaking things on your hands. WHY do you have to choose one tense? Because that's the rule? If it doesn't serve the story, and you break the rule with elegance and confidence, and your readers are illuminated and not confused, well then, break the rule. In other words, both past and present tense may be perfect for your narrator's confused mind.
Know this though: you're setting a very high degree of difficulty in this trip across the balance beam. Slip, wobble, or somehow miss a step and you're on the ground, not on the beam. Or above the beam!
To answer your question: when I open a manuscript or read pages with a query I don't think "oh blerg, present tense!" I read the pages or the manuscript and if the story isn't working, I might suggest a shift of tense.
In other words, my preference is for stories that work rather than for a specific tense or POV.
If you were my client and we were discussing what to do with this story, I'd tell you to finish it and see if the use of two tenses works. Often the only way to know is proceed ahead.