Define your mission. Do you want to travel longer distances, or just do relatively local sightseeing and $100 hamburger runs? How much weight do you want to be able to carry on a trip?
I would take a 182 over a Dakota any day of the week, mainly because the 182 is more comfortable and slightly bigger inside. Don't listen to the high-wing/low-wing nonsense, it really doesn't matter where the wing is.
For what it's worth, I have about 150 hours in DA40s, 500 hours in 182s, and probably 400 hours in PA28s including the Dakota.
But, also wondering what your budget is? Like for like, a Dakota is probably cheaper than a 182, but like I said, not as nice in terms of comfort. Neither one of them will fly anywhere near as nicely as a DA40. Looking at 182Q models, it looks like they're generally in the $90K-$150K range for asking prices. While there aren't nearly as many Diamonds for sale, a non-glass panel one like
this is right in that same range. There will be far fewer of these for sale (the "steam gauge" DA40s were only produced from 2001-2003) but if you can afford the nicer 182s, you can also afford an older DA40.
In addition, an "older" DA40 is still going to be 20 years younger than a 182. I would expect your operating costs on the DA40 to be around $30/hr lower than the 182Q, so if you're getting a loan for the purchase price, be sure to factor that in as well - You can probably afford more DA40 than 182, provided the DA40 carries enough weight to meet your mission.