I've been using Bibarel teams exclusively for the past few days and here are my two cents. First off, Bibarel is best used as a late game cleaner. My most successful strategy has been using hazards and constant pressure to wear down my opponents team to the point where the fast frail mons can be picked off with boosted priority and the slower bulky mons can be muscled through with a +4 Return. Bibarel is usually just bulky enough to take a hit while setting up Swords Dance and can then proceed to wreck havoc. Back in gen 5 I used Feraligatr as a late game sweeper and I would say gen 7 Bibarel is very similar to that.
Bibarel @ Silk Scarf
Ability: Simple
EVs: 80 HP / 252 Atk / 4 Def / 172 Spe
Adamant Nature
- Swords Dance
- Quick Attack
- Aqua Jet
- Return
This right here is Bibarel's best set. I chose Return over Double-Edge because Bibarel will often need to take a hit to set up and I don't want the recoil killing me mid-sweep. This moveslot will generally be used against slow, bulky mons with a lot of hp so you can bet that the recoil caused by Double-Edge would be a decent amount too. I chose Silk Scarf over Life Orb for similar reasons as well. Also, using a Life Orb brings the mind games of your opponent switching around at the end of your sweep to attempt to stall out the recoil. Bibarel is especially vulnerable to this phenomena because it's priority moves often won't dent the switch-ins too much resulting in so many moves being used to complete the sweep that the Life Orb recoil will add up too fast killing you first. The extra damage from Aqua Jet won't be missed too much and I tend to think of it almost as a coverage move. Aqua Jet hits many common resistances to Quick Attack super effectively such as Heatran, Marowak-Alola, and Rocky types so the extra damage isn't usually necessary. I've also found that Return and Silk Scarf are much more useful than Aqua Tail/Waterfall and Splash Plate because most opponents try and stop Bibarel with bulky grass and water types that are hit neutrally by Return. Return also has a higher base power.
The EVs on this set are nonnegotiable. The speed EVs are used to outspeed most bulky walls up to uninvested Mega Venusaur in order to bop them with Return first. Attack is maximized and the rest are dumped into bulk.
Like I said before, Bibarel is best used as a late game sweeper. Once the opponent's pokemon are worn down appropriately, Bibarel can clean surprisingly well after a Swords Dance boost (which isn't too hard to get). It's dual STAB priority sets it apart from everything else in OU and is incredible in tandem with Simple Swords Dance. Bibarel has just enough speed to outspeed bulky walls and just enough power to take out faster pokemon after a boost. However, wearing everything down just a little bit first is really key here. I also find Bibarel good at its role because no one expects it. Nobody is thinking "better keep my Ferrothorn alive to stop a Bibarel sweep" which they probably would think of for something such as Gyarados. If anything, people assume bulky grass and water types such as Toxapex and Mega Venusaur blanket check it which is not true at all after a Swords Dance boost and a teeny bit of prior damage (cannot stress enough how key this little bit of prior damage is!).
Here are some replays of my Bibarel set in action. Both are against respectable OU teams and Bibarel sweeps at least the last 5 pokemon in both replays late game after my strategy has been properly executed.
http://replay.pokemonshowdown.com/gen7pokebankou-483903877
http://replay.pokemonshowdown.com/gen7pokebankou-484134462
The only change to my set I would be willing to consider is Double-Edge > Return just to hit those fat walls slightly harder. I haven't tested this out yet but I still think Return is better. Also, I'm very against Life Orb and basically any other Bibarel set for the reasons I already provided. Maybe Life Orb with Return could work but if I still think Double-Edge and no Life Orb would better if I were to make any changes to my set. Regardless, I think both Life Orb and Double-Edge as recommended by the OP is a terrible choice.
In conclusion, I think Bibarel is currently on the lower end of viablity in OU and its only place is as a late game sweeper with this set.
EDIT: If anyone disagrees with anything I said please feel free to explain because I'm always up for debate and open to new ideas