I love what I do but I hate the place I do it in. I spent a long time training and studying for this career, and around 18 months ago got what I thought was my dream job. It was actually a step above where I'd applied for - the boss offered me a management role on top of the "real" job if that makes sense. It's quite good money and in a field where jobs are really hard to find.
But. I HATE it here. My boss is useless. Unprofessional, disorganized, lands projects on you with no thought of strategy, engages in practices which I find unethical, has no people skills... I could go on and on. There is a also a key member of staff who is her friend an who is beyond shite at her job and that makes my job more difficult. I'm doing more hours than I'm paid for, expected to clean up all the shit and deal with my own very stressful job on top of cleaning up my boss's messes and looking like an idiot to the other employees, who know I'm constantly kept in the dark. As in they'll say "Oh I hear about X project" and it'll be the first I've heard of it. I'll say to boss "Are we doing X now?" and she'll reply something like "Oh yes I decided that last week. So can you organise [XYZ] to make that happen." and it drives me crazy. I'm constantly on edge and never know what's going to happen. But on paper the experience I'm getting is brilliant.
Now a job has been advertised in an organisation I respect, and where there is room for advancement in a few years (there's no level between me and my manager in the current place and it's her baby so she's sadly going nowhere.) But it's less hours, and less money, and I'll be back to staff level, not management. I'd feel a bit of a failure going backwards, and worry that people will think I just couldn't cut it at management level but it's not that, honestly. I'm not in a great place financially but I'll be better in a few months when I've paid my credit card off, but lower salary might leave things quite tight. although DP has a good job and is supportive - he's like "Get out of that place!" Maybe because I moan to him every night 
Added complication - we're TTC. If I did get the new one I wouldn't be there long enough for maternity pay, only statutory, and that really would make things difficult, whereas if I stay here and it happens at least I'd get to make them pay me for 6 months of not being here!! And then again, it might not even happen so it might be stupid to stay here just in case and let this job pass me by - they really are like gold dust where I live.
So what would you advise? Stay in my good job that makes me tear my hair out and gives me palpitations, or take a less stress but lower paid job where I might advance in a few years but will be going backwards for now.