I know he still oozes but all you have to do is walk away -.- You'll get at most one or two seconds. 

By that logic, Rook blows UB out of the water because his towers still shoot while he is Oozed.

Even then, Magnificent Presense and Healing Wind II still work while Orb'd. If you are focus fired as Sedna and you orb while everyone is still around you, you're still contributing to your allies by giving them the large monk heals. Sure, same logic with UB (run into the mob then Ooze), but it's easier to guarantee that your allies will be around you than your enemies. 

You can also just do "more" with an Orb as Sedna. Ice TB puts Deep Freeze IV on you, you Orb. Debuff removed, and you didn't have to waste the heal on yourself. UB spits on you, you Orb. Don't have to waste heal on yourself. The primary benefit is that you rarely have to "waste" heals on yourself. Even if you do, Heal > Orb > Heal > Silence is a fantastic stall rotation and it lasts a full 10 seconds. 

Basically, saying that because Ooze works through Orb and therefore makes it the best is an incomplete argument. 

If I'm using Orb and it's forcing your team to walk away every time that's great.  If I'm UB and I see Sedna Orb I just move into better position and still kill you when you come out of it.  If you see me Orb you run away or take my ooze and spit damage, clearly one outcome's a little better. Orb is most effective when it's a full on 3 vs 3 fight which means the other team can't always afford to just walk away.

You're not entirely right about Rook, if he orbs in a full tower farm yea that's going to do a lot of damage but the towers also get distracted by the grunts and minions, UB's guaranteed to be doing damage to anyone who's around him while Orb'd.   

@Split: Orb was a must-buy for Rook before people started using Sigils. Orb is also good when playing with scrubs but I figured it was obvious enough it wasn't worth mentioning. 

You also can't just change from my 3v3 argument and put that into a 1v1 argument. Generally if you Orb in a SvUB it's used at the very beginning of the fight to rinse the initial spit (assuming not standing on a bad flag). MP with Sedna allows her to rinse one out of every 3 spits. 

Going back to the 3v3, if Team A focus fires the Sedna (as they ought to do), and she either Heal > Orbs > Heals or proactively Orbs, her aura buffs are still contributing to the team.  MP + HW II + Counter Healing > Ooze in a 3v3, espiecially since all 3 of her auras have a larger radius.

Also, UB contributes far more auto-attack damage than Sedna, so really it's

MP + HW II + Counter Healing - Sedna's AA > Ooze - UB's AA

If instead, Team A focus fires the Sedna but the UB has it instead the Sedna gets pushed back and out while the UB wails on them. Then Sedna has to sit over in the corner and cower and provide long range support/heals for the UB with Orb who never used it. Also, Sedna benefits more from the passive HP and Armor bonuses because she has a small health pool and the +500 HP helps a ton. 

That said, Sedna does have really poor timing for acquiring Orb, which is why you usually don't see it on her and see it on UB or Rook instead. Initial Monks + early investment in Citadel + gearing + eventual investment in better Monks + contributing to purchase units means that she won't have the ability to easily drop the 3500g until WS 9 or so, usually. UB can get it much earlier and he can abuse it during that window.

However, the UB dropping it in front of the crystal (after a few warscores pass, and possibly with the Sedna dropping an item in return as to not gimp the UB) and the Sedna picking it up can be a better choice than leaving it on the UB depending on the game flow. Against gank teams like DA + Erebus + Oak, then the UB should definitely keep it, though the Sedna will be hunted too. 

Lol, and once you start distorting what others say/write McShane we should all just ignore you.

He DIDN'T say there's anything better than Ooze in 3v3, his point was: UB loses more (damage dealing with his omgwtfbbq AA, his main role in DG) when he Orbs than what Sedna loses when she Orbs (she still provides healing aura-counter healing, enhanced monk heals, decreased cooldowns aura if MP, she's still a friendly healer/supporter in Orb, her main role in DG).

I don't necessarily agree with Sedna being the best candidate for Orb, though. UB is the melee damage dealer/tank in the game, so he's the most likely to be in the frontline, hence the most likely to be the target, hence the better chances to nullify Pents/Bites/Fireballs/Hammer SLams etc. etc. if he's the one carrying and activating the Orb, while ALSO ooze-damaging nearby enemies without tacking damage himself.

Same with Rook, he's Huge, slow and low armored, so he's a very likely target for the whole enemy team, and his towers can deal a lot of damage (much more than ooze, and you cant walk out towers range as easily as out of ooze range) if he orbs in the middle of his tower farm. On top of that, he benefits a lot more from the additional HP and especially ARMOR that Orb provides, given his low base armor nature.

So that's why i put UB and Rook on the top of my OoD list. I might add Sedna as a good 3rd candidate in the OP, we'll see. I find ranged characters the less likely to benefit from OoD, though it might be somewaht useful on a Staff of Renewal Reg late game, the decreased cooldowns Staff provies makes OoD more useful and can help him hold/retake an enemy-giants/DGs infested HP/portal flag lol.

Still, Staff of Renewall Reg will get greater benefits from Wand of Speed, and at much lower price, than from OoD IMHO.  

Btw, on the cooldowns note, it might not be the best idea to Orb when TB puts a DF IV on you, unless you enjoy 100+ secs cooldowns on it    or are planning to sell it inmediately after the current gank/fight lol.

AFAIK you can't drop items while they are in cooldown....