Easiest games/engines to import 3d models?

I like creating 3d models, houses, trains,etc. and then exporting them to games, where there are trees, water, AI and stuff, so basically to see them as a part of a ,living world".

I used to do this a few years ago on the Crysis game engine (both for Crysis 1 and 2), as well as the unreal engine, but I forgot most of it in the mean time. So what game should I try to export my models to?

Also, Unity is probably the easiest engine to export to, but I can’t find some finished assets, there is loads of cartoonish assets and not entirely finished cars on the unity store, but I don’t want to waste hours making cars drive-able, making AI,etc, I just want to import a 3d model in a game world like Crysis, where all the assets are finished and I only have to select them and place them on the map.

Gta V or Garry’s mod would also be great, but I suppose that there’s a lot of modding required there.