Pathfinder 2e, Savage Worlds, and WHFRP 4e all have fully featured implementations, albeit at additional cost for the official, pre-done content. PF2 doesn’t have an additional cost for rules compendiums and such due to the SRD being available.
I’ve run all three via Foundry. Of the three, PF2 makes incredible use of the system. The Outlaws of Alkenstar AP is available as a module from Paizo and is very well implemented. Maps, LoS, music, it’s all there and ready to go.
The WHFRP 4e official content is also very, very good. If your a battle map player additional work may be needed but if your primarily a theater of the mind person I don’t think you’d need to do much more than purchase the content.
I have the official Savage Worlds and Savage Pathfinder Foundry products. When I’ve run them I’ve used converted or home brew content. From a rules/compendium/ standpoint they are both very good, but not as good as the PF2/WHFRP implementations are.
I’ve also played with the 3.5 rule set. It’s heavily supported by third parties and is excellent. It integrates with a lot of the bells and whistles out of the box so to speak.