Your humanoid companion varies depending on certain factors. Non Light Touch Laser Builds: Use ED-E due to one rank of his ultimate perk raising beam damage. House, Legion, or NCR routes (unless you can form a truce between NCR and the brotherhood, you may need to replay Veronica with Lily seeing as how she isn't involved with any faction. If you destroy the brotherhood of steel bunker in the Mr. Non Light Touch Criticals Builds (Long Rage): Rex and either Veronica or Lily.
Both these increases make up for your lower DT because you wear light armor. Drinking whiskey or wasteland tequila raises your DT, depending on your survival skill level. When fully upgraded, ED-E raises your DT a little. Seeing as how my methods of playing this game differ from probably everyone else, I do things differently. I've done some research and experimented in the game with different companions and have come to the following conclusions.