Eh. Lets see and compare them, major fights with context which matters a lot and most people don't see it (I like both Merab and Khabib) :
Key :
C level = ok fighter
B level = good fighter
A level = very good fighter
S level = elite
Khabib :
- past prime RDA who wasn't elite by that time but he was still very good and is to this day (He gave problems to Gamrot who is very good, lost via injury to Neal next fight), A level win
- Edson Barboza during that time was A level fighter. After losing he was hit and miss but he is still going strong. Now is B.
- Conor was in his peak when he fought Eagle. S level win.
- Dustin was in his peak when they fought. S level.
- Gaethje just like fighters above - elite.
Additionally :
- Gleison Tibau who was only B level fighter was juiced to the gills when he fought Nurma. His enhanced cardio and strength give him problems. This was only fight when Khabib had problems. Enhancements really ascended Tibau to someone who was A level and gave problems to pre-prime Khabib. After their fight Gleison was suspended for using banned substances. When he went back clean he was steamrolled by pre-prime Islam who was (and still is by his own words) Khabibs bitch in gym/sparrings.
Plus Khabib never was in real trouble, never bleed and had aura of invincibilty.
Now Merab :
- past prime Jose Aldo - who was still very good at that point but no longer elite. He was very passive during their fight. A level win.
- Petr Yan who was in weird stage of his carreer during that fight. (lost to Ajlo via DQ fight in which he dominated, then bounced back with very good Sandhagen, then fairly lost split to Aljo again then robbery versus Suga and then finally fought Merab but seemed disheartened and off during that fight). Still, no excuses. Elite level win in my book.
- Cejudo went back from retirement but even with ring rust during his tenure he looked elite. S level win.
- Suga Sean - this is interesting. O'Malley was outclassed heavily but thing is.. while I think Sean is very skilled he is 'only' very good - not elite. He was champion by accident. Yan fight was robbery, Aljo seemed very off during their fight and Marlon Vera isn't elite. I would controversially say that Sean is A level only. Both Merab and Umar would maul him. Well Machine already did.
- Umar - I thought Umar was overhyped because of his name because only major win was against very good (not elite) Sandhagen but after UFC 311 he has shown that he belongs to elites. Now I believe that top 3 BW's are Merab (obviously), Umar (he had showing) and Petr Yan if he is in his top game. Nonetheless Umar is elite. S level win.
Summary :
Not counting B and C level wins (or on that matter D, E, etc...) Khabib has 3 elite wins which were coincidentally his title fights and 3 A level wins.
Meanwhile Merab has also 3 elite wins and 2 A level wins. Shockingly it is closer than I thought. I thought that Khabib would be clear winner but statistics are saying otherwise.