Stock answer to this question is a C182, unless something particular about your mission points elsewhere.
Why? The 182 is easy to buy, easy to maintain, easy to insure, easy to fly, carries a heavy load, lands darn near anywhere and on anything, and is easy to sell if/when your mission changes to warrant it.
That said:
I have a family, who would be the main people flying with me. I will never need more than a 4 seater. I do go a lot of places around the country for work so flying there my self sounds like a great way to get long cross country trips in. Outside of that the plane will largely be used for occasionally weekend trips within 500nm and then just the local events etc. I don’t see my self flying more than 125-150 hours a year.
500nm is a one-hop flight in a 182 or anything faster, so that's good. But the "around the country" tells me you might want something slightly faster, though your relatively low experience level says maybe you should save that for the second plane.
my question is- as a first time plane owner should I just go for the plane I want (leaning between a 182 p/q/r or Dakota) or get a simpler plane first like an archer or Cherokee, experience ownership in something similar and get a more capable plane later? For people insimilar situation that went one route or another - do you have any regrets and wish you did it differently?
If you can afford the plane you want, with sufficient reserves available for surprises, get the plane you want. Buying a trainer isn't going to expand your reach, and it's going to drain your bank account for... What exactly? To say you own it? If the trainer isn't the plane for your mission (and it usually isn't once your training is done!) then don't buy a trainer.
500nm weekend trip id want something faster. That will get old fast. I’d look at an A36 bonanza, speed, and a true 4 place with luggage and room for extra pax if ever needed.
The difference there will be about 40-45 minutes. Bo will be about 3.1, 182 will be about 3.8. Worth considering whether that difference is worth it.
Why are Comanches so much lower priced than other planes?
Well... Let's look at what's comparable. Bonanzas, Mooneys, Cirri... All of which have remained in production to much more recent times while the Comanche hasn't been produced since 1972.
Of course, the Cirri have not been in production long enough that they're as cheap as the Comanches on the used market. The oldest Cirrus is 25 years old, the newest Comanche is 52. Newer stuff (usually) costs more.
The Comanche was always known as the "Poor Man's Bonanza", so presumably its initial purchase price was lower. Beeches are nice planes, but somehow they have a nearly cultlike following and so their prices are always inflated relative to similar types of aircraft.
If you look at 52-year-old Mooney M20Cs, you'll probably find some that are comparably priced with the PA24-180s. But you'll find lots of newer Mooneys that cost more too.
Overall, the Comanche is one of the best performance bangs for your purchase buck in aviation. It costs more to maintain an aircraft that old, but I know lots of people who are very happy with their Comanches and I've always liked them.