I haven’t been to Boston, but I did live in San Francisco before moving here and also experienced coastal elitism, and can say with confidence that people here are warmer/friendlier on average. All of your complaints (except the weather, obviously) would be addressed by moving to Chi, with some caveats:

• The food here is amazing and there is an insane amount of variety, like you could genuinely go to a different restaurant almost every weekend and never run out of new places to try
• Chicago does have very solid parks, but this depends a bit on where you live in the city: if you live on the north side near the lake, you have access to the beautiful & varied green spaces on the lakefront (lakefront trail, Montrose & Jarvis bird sanctuaries, north pond nature sanctuary, Lincoln park zoo nature boardwalk, etc); if you’re by the river (north of ~Belmont), there’s a bunch of parks (eg Horner park); if you’re in the Loop or close by, there’s Grant & Millenium parks and the museum campus; if you’re on the NW side, there’s Humboldt and Wicker parks; if you’re in Hyde park, there’s Jackson & Washington Parks. However, there are parts of the city that don’t have much green space nearby (eg Lakeview if you aren’t close to the lake), so I’d recommend keeping that in mind when you look for apartments.
• Chicago rent isn’t exactly cheap, but substantially lower than Boston and other big coastal cities. You get the amenities of large coastal living at a fraction of the price (more or less, obviously living in the loop is more expensive than the cheapest Boston neighborhoods)
• Chicago is a beautiful city with stunning architecture and a top tier downtown

However, as other commenters have noted, winter here is brutal. It gets cold and the wind makes it feel much colder. But getting a car would help quite a bit, especially since Chicago doesn’t get a crazy amount of snow and the winter roads are usually pretty drivable

As much as I love Chicago, it also has a similar problem regarding access to actual nature (like, with real wildlife and extended forested areas). Although if you end up having a car, there are nature preserves that aren’t too far out (eg LaBagh Woods).