for me.... its Doflamingo and Boa....
Doflamingo is one of the strongest (just one) because apparently using observation on the latest one piece show..it's just like he's using strings to fight his enemies... many anime showing characters controlling their enemies is through hypnosis (mind going blank)... puppeteer (using strings to control or cut)...blood controlling (via use of water inside the body)...threatening (like if they don't obey their friend/family will be killed)....fear (felt because of the enemies over whelming power and has no match)...betting (when you lose you are to obey the enemies command)..and so on and so forth... but apparently...i'll go for the usage of unseen strings for Doflamingo and he's very fast when using it...but when against logia users i just wonder..because he asks crocodile for permission because crocodile's DF ability is logia----- sand...he might become really tough tough tough to beat if he could use seastone strings without affecting his self...
Boa is one also of my characters, if have you seen her fight...true its just like sanji's style but with DF ability and haki that's why she can take on logia users just like smoker when she kicked him too easily and when she is about to save luffy from aokiji's ice spear (but apparently marco saved luffy first from the attack)...she would eventually fight aokiji if she is the one to save him betting that she could fight equally....she also took on some pacifitas too easily.... she can also use the king's haki just as her sister's statement of seeing luffy use king's haki when they were fighting... also you could have seen how she just destroys any weapons (i don't know about seastone weapons) that her kick pondered upon meaning she could match that of hawkeye's sword... she could also turn a large quantity of humans at the same time into stone....
Blackbeard... i don't like him though... [take note of the term] with great intelligence and prodigious skill (thanking that he neither have any)... that gravity ability would become too powerful that could just destroy things that is on its path easily (like stop a persons movement totally by putting gravity around that person making that person unable to bear the weight and not to move)...but since he's just using it at its mediocre's knowledge of gravity it might be fine ... i hate it too when at some point he gains whitebeard's DF ability....
Kuma's ability to deflect and teleport is also terrifying along with laser attacks.... if the opponent is not that skilled or intelligent... it's hard to fight kuma but i think a lot of fighters could beat him..how?...for example a surprise attack..or using lightspeed attacks...or invisible attacks....many has those in the show.
Hawkeye, i still don't know if he have any other kind of abilities aside from the usage of his sword with unknown element...but typically he's strong to cut down hundreds of enemies in one slash...but some could match him like a captain under whitebeard's command or in the future zoro maybe....
Moria....well his kinda weak after Luffy beat him down...but those kind of shadow ability shown by the producers are just half or not even, maybe so that there won't be too much graphics..example of terrifying ability is to make his enemies move just like his by shadow connecting... or just pull all shadows of enemies in broad daylight by insighting his shadow over them turning his enemies to dust... also by hiding weapons in his shadow and attack his enemies on blind spots by shadow transportation....etc....
Crocodile...we have seen his much srength and abilities and weakness but i say his strong since he's logia type DF eater after all...nothing much to say...
Jimbei is also strong being able to use the water around him and fight using karate but many could also match him.....he got beaten quite when saving ace but could take a lot...i mean a lot of lot of lot.... he has a high stamina..... making him truely a formidable opponent...
0. kuma - more a pacifista than actual kuma so dunno if he counts
1. mihawk - strongest warlord due to the fact he was owning luffy and fought on par with shanks multiple times.
2. blackbeard if he counts - strongest logia, can cancel fruit powers.
3. law - hax beyond belief, beat a vice admiral who was a logia by taking his heart
4. doflamingo - seems badass but hasnt really done much
5. croc if he counts - number 1t in the desert. if not, then hes at 5.
6. hancock - beats anyone who is a perv or cant dodge her kicks/arrows.
but all of them are incredibly strong
Moria --> Crocodile --> Hancock --> Jimbei --> Kuma --> Mihawk --> Teach --> Trafalgar Law- -> Domflamingo
Moria is obviously the weakest one due to the fact that he doesn't even fight that well himself.
Crocodile went down really easy but still was able to take Luffy out twice before he finally lost.
Hancock may have the lowest bounty but that proves she earned her title fast and she has Haki and ability to turn others to stone.
Jimbei is a fishman and strong. But his easy heart is a huge weakness and so he's near the middle.
Kuma can teleport and move things at the speed of light as well as fire lasers. Since he lost his free will he is probably more of a monster now.
Mihawk is an obvious badass being the strongest swordsman and owning the world's strongest Black Sword.
Teach having a Paramecia devil fruit on line with Logia type and being a total stud. Being able to defeat Ace by himself. Also controls other devil fruit powers now due to a mysterious power.
Trafalgar Law is a stud. His ability to cut and rearrange stuff in his room is overwhelming powerful and even enough to take down a pacifista before the timeskip.
Domflamingo is the obvious strongest. His alias as the Joker and being the strongest Underworld Broker is fear enough itself. Having the string string fruit is dangerous to control his enemy and cut them. He took down Smoker without sweating in the least after the events on Punk Hazard.
You guys really underestimate Crocodile and overestimate Doflamingo. He's just a lazy ass who doesn't get attacked a lot and if he is, all he does is trying to avoid the attacks without much offensive capability. On the other hand Crocodile has flexibility, strength, speed, invisibility, invincibility, one hit KO (dehydration), a very useful tool (the poisonous hook), extreme intelligence and is skilled to perfection with his ability.
Jinbe is strong in the sea, but on land he's useless.
Boa is not such a big shot the only thing that makes her worth mentioning is her ability to turn people into stone.
Hawk-Eyes is skilled, strong but predictable and a devil fruit can easily outfight him.
Kuma is hella strong, hella fast, flexible, but he's a bit easy target and i believe he has vital weaknesses that are a bit hard to find.
As for Moria is a disgrace for the warlords no skill, no strength, no flexibility, no durability, and not any real offensive ability.
Blackbeard is very very strong but totally unskilled, way too confortable and let's his opponents get first strike, though he has a lot of potential.
Buggy's personality makes him very bad at fighting because he's scared of everyone he thinks that is stronger than him, he's not serious, he doesn't have much potential and any skill at all.
Trafalgar is intelligent, has more room for improvement, he's flexible, strong by many views but he's too slow.