This is all going to be more NSR
Cairn seems like an obvious one. It's classic fantasy that will be pretty familiar to people, it has a good number of adventures as well as adventures for other systems that have been converted, and also all the rules are totally free.
Mausritter (modern, but nice) and liminal horror (modern, but horror) are also good. These are all Into the Odd games, there are a lot of hacks of this system for different settings and I feel like you can't really go wrong there.
I'll also recommend Fallen, especially for solo games. It's more like gothic fantasy. It has some really good random tables. I use the oracle deck for other games all the time.