For me its the area between Whiterun and Eastmarch, because there is a beautiful wood with a high waterfall. Looks awsome.

Hjaalmarch, Morthal and the swamps. Stunning beautiful atmosphere.

Markarth and pretty much all of the Reach.

I like the Riverwood area. It has River & Wood!!! nice place.

The Rift. It's my favorite area in any of the Elder Scrolls games. The Birch trees, autumnal colors, waterfalls, I love everything about the region. I would gladly live there in real life.

I like Hjaalmarch, Haafingar, WInterhold, Whiterun Hold, and whichever hold has the hot springs (?).