I like the Ergon GP5 grips and bar ends, I've had them on most of my bikes for at least the last 12 years, they're now pretty much the default on new Thorns, I was using them for a few years before that.
Then, whatever bar puts those in a suitable place, for me that's a pretty standard straight bar, no more than a 5 degree bend. I think the current Thorn bars are about that. I do sometimes wonder if I might benefit from a slightly wider bar, but I have too many cycle barriers to fit through every week which would be awkward with anything wider.
I'm not sure you're going to get any useful information from this question. People, inc me, can only tell you what they like and maybe what they don't. They, like me, may have tried a few before finding that, but then stopped trying anything else.
What I do know is that a lot problems associated with poor bar set up are actually caused by some other element of bike fit. If you get the rest of that perfect, there's probably* a fair range of acceptable hand positions, if you don't, then no amount of messing with the bars will solve it. There's a fair difference in reach between my bikes, I think around 5cm from the largest to smallest, I notice this when I change bikes, but it's forgotten within the first few miles.
* I only say probably in case there's someone who it doesn't apply to, though I'm doubtful there is.
EDIT - My hand position while cruising on flat bars with GP5's, is closer to mickeg's photo on drop bars than anything I could achieve with JohnR's flat bars.