In my most honest opinion, I'm going to have to give this one to Jellicent. Though Gourgeist does have a higher base total star, it's movepool isn't anywhere near as good as Jellicent's. It does get some good moves Like Phantom Force, Shaodw Sneak, and even Giga Impact, and combined with its solid Attack stay and an equally solid Defense stat, it makes for a great Pokemon. The only things that limits this Pokemon is it's typing.
Jellicent on the other hand has a slight advantage. Although it has a total base stat less than that of Gourgeist, it's a bulky Pokemon, and what do we love most about bulky Pokemon? The ability for them to survive longer, which is a great segway into the next point. One of the best moves that Jellicent has is Recover, and who doesn't love to recover hp? Combine that with Scald for a burn chance, Shadow Ball for them scary ghost, and if you're feeling risky an ice type move to handle any pesky Dragon/Grass/Ground/Flying Pokemon that might come your way.
In conclusion if we're relying strictly in Stats alone, then yes, Gourgeist is the better of the two. If it's movepool solely, then that win goes to Jellicent. Overall Jellicent is probably going to be your best option. It's bulkier and has a better moveset. The idea and concept behind Gourgeist is nice, but Jellicent outclasses it. Hopes this helps :D
