Here's my honest opinion. I'm trying to be as open on this conversation as possible. Not trying to be a fan of either one, funny, sarcastic, or anything like that.First thing, yes I am a fan of both. Love how they fight. Knew Jones was the Champ after he beat up Bonnar.

https://i.ytimg.com/vi/79bSx93HdKU/maxresdefault.jpg

DC hosted a wrestling camp of our gym in CA before he was famous in MMA. Nice guy. Got that out of the way.This conversation is interesting because of the history and sheer differences between the two.

We have Jones:

http://www.latimes.com/resizer/fdqiHNHr6jCK8026zNEdF-KCJA4=/1400x0/arc-anglerfish-arc2-prod-tronc.s3.amazonaws.com/public/P2M24CIXENHNRN55B2QQHGDOWA.jpg

Truly undefeated.
Athletic as can be.
Great grappler.
Dynamic striker.
Beat numerous former champions.
Dominant all around as a prospect, contender, and Champion.
UFC Champion.
Personal issues.
Drug issues.
Partying issues.
Legal issues.
USADA issues.
Got popped for steroids twice. First was "dick pills", this time who knows. Has stories told about him hiding from drug tests in comp. Covington now saying he's been a user since college, which you can't take him for his word, but I have read this before by some old classmate of his.

Then we have DC:

http://media.ufc.tv/generated_images_sorted/Media/648/648379/UFC-220-Daniel-Cormier-Octagon-Interview_648379_OpenGraphImage.jpg

OSU Champion Wrestler.
Olympic Team Wrestler.
Undefeated HW MMA Fighter.
StrikeForce HW Champion.
UFC LHW Champion.
1 loss at LHW. Technically 2 but was overturned. Both to Jones. Though he clearly lost both, it wasn't the worst one sided beatdowns I've ever seen. First fight was kind of boring tbh. Second fight was getting REAL INTERESTING before the headkick he was losing but it was getting wild with DCs new Fedor style punches lol. I wonder if Jones didn't have that giant reach advantage.....
Family man.
No USADA pops.
Class act.
Going for 2 belts in the UFC at the same time.

It's hard to say Jones is not the LHW Goat. But, since the drug scandals tainting his legacy I have to account for that the same way I have to feel about Silva. It sucks, but PEDs do give advantages and are against the rules. Yes his skill would be the same, etc. But PEDs allow people to train harder, longer, etc..has many benefits.
With all of that, I still have to say Jones is the best LHW in the world. Honestly, if you had Strikeforce/Early UFC DC vs Jones at HW it could be a totally different fight. But, we saw what oldish DC vs Jones looks like so I think we get the picture. Though I'd still love to see them at HW. DC is a different animal at HW.If DC wins the HW title you have to at least put him in the historic icon category. Rather he beat Jones or not is irrelevant because if he beats Stipe he just beat the baddest man on the planet/most dominant HW Champ in UFC history at 40 years old. I'd have to say he is a GOAT. Not THE GOAT.THE GOAT IS MIGHTY MOUSE or GSP!

My list is as follows not in any order.

Mighty Mouse
GSP
Fedor
Silva
Jones
DC (if he beats Stipe)
Stipe
Aldo
Cruz
Honorable mention: Cain, Werdum, BJ, Hughes, Liddell, Overeem, Conor (only because he got 2 belts), Randy C.