Until official DLC and player mods are released, Skyrim will always be more superior in terms of it's content. But I do feel FO4 factions, faction stories and side quests are somewhat lacking and linear at this point. Skyrim had over a dozen diverse factions with backstories going back to TES Arena. With the exception of the Civil War factions, there was a lot of room for overlap in joining these quests. Because you could side with the majority of these factions without penalty to your sandbox game play, the MQ, or other quests. Case in point: in FO4, you're extremely limited in your ability to do faction quests for the Railroad, BoS and Institute. Because membership in these is mandatory before the game will allow you to progress doing faction quests. And the further you progress in faction quests for say the Railroad, the more you undermine your PC ability to do faction quests for other factions (with the Institute in particular).
In contrast with Skyrim, there was FAR more flexibility in joining factions. Especially since some factions (like the TG and DB) complimented each other in terms of particular character builds (i.e. stealth, assassin/thief builds). And the same worked for dissimilar factions like the Mages Guild. So you could become the DB AND TG AND Mages Guildmasters while being a Vampire Lord who trying to advance in the Companions. And a sixually liberated priest or disciple of Mara, spreading the love of this Aedra to the denizens of Skyrim with the Temple Quests. Or at same time, be a valiant adventurer questing for a Guiness Book record number of arrows to the knee -- while solving the Dungeon and Daedric quests. There was a LOT vanilla content and quest lines outside of the MQ that kept people occupied before mods or official DLC ever started coming out TBH.
I don't feel the same way as of yet with FO4. Perhaps because I'm still playing a heavily modded TTW version of FO3 and NV. And alternating between Project Brasil. So I guess I'm spoiled for all those amazing FO3/NV mods like PN, AWOP, Craftmaster, Advanced Recon, AND all of Someguy's incredibly immersive mods. And official DLC like Gun Runner's Arsenal. Or small immersion touch mods like being able to smoke or allow you character to take a bath in showers/bathtubs (when dirty or injured/bloody). Or the need to eat regularly and so need to use the bathrooms/toilets you find around the wasteland because they now have modded stomachs and bladders.
So I feel this poll is somewhat premature. It's only fair to wait and see what Beth releases for the DLC. And what magic the modding community can perform to fill whatever gaps in content that Beth may have missed.