Which factory image to download? I have a Nexus 5 (LG-D821) 32 GB and am currently on build LMY47D, I want to upgrade to latest version of Android 6 ATM the latest version is 6.0.1 but there are like 4 builds for this version. Which one should I download?
According to comparisons on the internet, they are the same, but updated versions (OTA) of each other. They are the smaller updates that you might witness sometimes when you are informed of a new software update.

In the webpage you provided, they are ordered chronologically, so MMB29V should be the newest. I recommend downloading MMB29V as that seems to be the latest OTA update, last updated 3rd March, 2016, and reportedly contains some security fixes as well. If you have stock recovery however, you might be able to update OTA with an earlier version.