Grenades and bombs scale with...
Power and crit and crit damage.
The conditions they leave tend to work best with condition duration, not with condition damage.
Bleed on the shrapnel grenade yes works best with condition damage, but that’s sort of it.
Poison, blind, chill and vuln work better with duration.
Bombs scale well with everything. Bomb #3, concussion bomb, gives something like 5 stacks of confusion in an AoE which ends up doing massive damage, more so than most of our other skills in certain situations. Bomb #2 gives a very solid aoe burn. Bomb #1 and Big Ol’ bomb scale very, very well with power and crit.
Grenades tend to favor power/crit over condition, but you still have some decent condition damage from incendiary explosives since you have 3 chances to crit with each grenade toss. Likewise Grenade 2 gives you a strong bleed on a 6s cooldown.