fire does more damage
combustion is better than hydras
or just use hydras, its slower gameplay but little more safe.
Both are gonna have immunity problems, so you'd farm areas with no immunes. Forb is nice too though since you freeze/slow things around you, pretty hard to die unless ur reckless.
https://projectdiablo2.miraheze.org/wiki/Zonesuse this link and sort by immune for whatever type you choose.