It's perfectly right to be a munchkin (I was in BG2 when building my "dream team" with Keldorn, for instance,buffed with dexterity bracelet and strength belt) and still to prefer companions for their story rather than their lack in some attributes. But, if there is some CON or MIGHT check that are party-based (in opposition of main character other attributes/skills), I would like to know if some companion have a decent CON or MIGHT : it will influence my party choice because an Obsidian NPC will always have more flavor than an an adventurer from the Adventurer's Hall.