Yankee Hotel Foxtrot is easily my favorite Wilco album, but Summerteeth is a good place to start as it contains a good amount of their more "accessible" songs, for lack of better description. So start with those two and that should give you a solid base to dive into the rest of their material.
I've been a big Wilco fan for over ten years now, but it still takes me about a year to fully immerse myself in each new album as they come out. There's just so much to take in, sonically. Such an amazing band, and they are so good to their fans.