The grenade slot, whether you use grenades or not, is always there. Why not have the very best one equipped?
What is the best vanilla grenade? What has the biggest blast radius? What does the most damage in the blast zone? Does it throw loose objects around or does it not? How long is the fuse time, and how is that calculated? How rare is it? What perks affect it, and what do the perks do for it? Does it have bonus damage against certain enemies?
"Vanilla" Grenade stats list(where i could find them on the wiki):
Baseball: d:101, r:93, w:1, "Silent" until explosion
Cryo: d:101, r:93, w: 0.5, Chance to slow
Frag: d:151, r:93, w:0.5, no bonus effect
Hal Gas: d:1, r:93, w:1, "enrages" enemies, very limited number
Inst Emp: d:150energy, r:93, w:0.5, Robot only, damage over time effect
Molotov: d51, r:93, w:0.5, Applies "burn"
Nuka: d:301+100rad, r:93, w:0.5, irradiates area
Plasma: d:150+150 energy , r:93 , w:0.5 , energy damage static (not affected by perks)
Pulse: d:150 energy, r:93, w:0.5, No bonus effect, no extra damage to bots as is often cited
So to me, at least on paper, plasma seems the best raw damage wise, except for maybe nuka, which has radiation damage which would theoretically heal muties and not affect robots. But how do the perk calculations play out? What about magazines? Are there hidden stats that do something not listed? Some grenades throw loose objects around the room, which dont? Is range the only factor in throwing distance, or is there something else that would affect throwing one farther?