Honestly, Skyrim with a few optimization mods ran quite smooth and stable, unlike FNV which was a complete mess and I was never able to play smoothly for more than 2 hours in a row (and it's the game I played the most). But yeah, Fallout 4 has been quite the disappointment... hopefully they'll soon be done with it and let Obsidian make another proper Fallout RPG with the "new" engine.