If by modern you mean Fallout 3 and beyond, then absolutely New Vegas and its DLCs. You will not get anything of a deep story from any of the other offerings except maybe Fallout 4's Far Harbor, but that comes too little too late if you might not tolerate Fallout 4's flaws to get there.

New Vegas doesn't play very well in terms of combat, hello Gamebryo engine, but it has a complex story with many possible directions and endings, and many factions that are much more than black and white. Your character's own dialogue is also far better written compared to Bethesda's offerings and has a lot more agency in the world. I think you will find enough to enjoy there as long as you can get past the hump of some middling (even for its time) shooting.

A lot of that can be owed to the writing staff similarities between the original Fallouts and New Vegas, Obsidian's strong point.