Kakashi's sharingan made him stronger or weaker
Kakashi Sharingan vs Kakashi no sharingan
Would Kakashi be stronger without Obito's sharingan. Please do not throw this idea out strait away
Kakashi was the Hokage elect and recognised as one of the strongest jounin in the village but he does not seem to be on a Sannin/Hokage battle level. I think you see this in the fight with Kakuzu that he seemed outclassed and naruto had passed him by that point before getting sage mode.
Kakashi no sharingan advantages
1. He would not have gained the traits of Obito. Ie late to training/less inspired to train and to be the best. Him going alone with his chidori at the start of the gaiden shows how he wanted to be able to take on elite ninjas on his own. Also remember how well Kakashi is able to analyse both Naruto and Sasuke to create training programs to best utilize their abilities you would think he would also be able to do this for himself. In manga 502, the flashback to Minato fighting the nine tails Gai wants to battle Kakashi but he does not want to train but rather play rock-paper-scissors
2. Creation of his own jutsu. At 13 he had created Chidori but it was incomplete because he did not have the eyes for it but still he had created a new elemental attack perfect if the enemy cannot counter. Also if you see the progress of chidori through Sasuke Kakashi may have been also able to make these improvements. He most likely has the rasengan at this point as well. I am guessing he learnt rasengan but without the ability to use both shape and elemental he used the same concept of chakra at a single point but just nature manipulation. You would think he would be able to create new jutsu if he was able to create Chidori at a young age. Since he gained the Sharingan he has created no new jutsu
3. Without a sharingan he would have been concentrating on other Jutsu. If he had already learnt the rasengan (presumed and explained in 2.) he may have looked at Minato's other ability's most notably his time space Jutsu. While it may have been impossible for him to learn and he would not have mastered it in the time they had left together (approx 1 year) he may have been able to gain the basics of this jutsu and master it over time. We do not know if kakashi ever looked at learning this jutsu but with gaining the sharingan he would have had to dedicate a lot of time to master it so would have never had a chance to learn space time jutsu. Also his mangekyou sharingan ability is a time space jutsu which may be his or Obito's affinity to time space jutsu's. Kakashi seems to not had Minato's technique explained to him at the start of the the gaiden he does not recognise the jutsu seal on the kunai he receives from Minato. This is not the only other technique kakashi may have concentrated on but he may have been better at ninjutsu. He definitely would not have more techniques than copycat kakashi but may have learnt how to utilise some better.
4. His progression as a Child. Graduated academy at 5 the youngest we see I think (Sarutobi, Sannin, Yamato, Minato[10?], Itachi. He got promoted to Chunin a year later (so 6) and was a jounin at 13 the same age as Itachi becoming a ANBU captain, Now Kakashi is slightly behind Itachi but Itachi's promotion may be seen as part of Danzou's plan while Kakashi's may have been because of lack of strength because of the war but anyway lets say they are very close at this point. When they do fight outside konoha Itachi is way ahead. the split of both of them may be down to kakashi gaining the sharingan.
5. Progression of masters and students the general rule. Now while students do not always surpass their masters (Sannin probably did not surbass the 3rd) they seem to get close or surpass them. Now it went the 2nd Hokage (do not think 1st was the 2nd's master just his brother so probably sparred a lot) to the 3rd who was around the same maybe stronger (haven't seen 2nd's total potential including his time space jutsu) to Jiraiya who was slightly weaker but still legendary to Minato stronger to Kakashi who seems a lot weaker. He may have been able to reach his full potential if he did not have the Sharingan.
6. Sharingan a massive chakra user. Kakashi does not have a huge amount of chakra and especially since he is not an Uchiha it uses a lot of his chakra very quickly.
7. His father. Had potential to reach his father's strength whose name made the sannin's 'Pale in comparison' so may have had potential to have more abilities in that line. Master the white chakra blades presuming they will have some advantage over just putting chakra into a normal blade as what is the point of the bloodline ability. I am presuming his old blade broke in gaiden as he was not very proficient at it yet or just his lack of chakra meant it was not very strong. May also have had another summon. While his current summon are dogs most others have a giant beast and I would say his father may have had contact with wolves as summons often go with users techniques.
8. Kakashi is not a natural sharingan user so it has more drawbacks and if Kakashi without a sharingan got used to fighting dojutsu he may exploit copycat kakashi abilities
Kakashi sharingan advantages
1. copycat ability. Could copy any Jutsu the other kakashi used
2. better genjutsu. while used with his copycat jutsu a sharingan would give him better genjutsu
3. better sight in taijutsu, can be seen with his ability to use chidori after gaining it
4. use of ninjustsu previously copied. Is meant to have learnt 1000 jutsu he has copied
5. space time jutsu where he can sort of insta-kill someone or rip a limb off. Normally needs time to use and only uses if necessary.
6. Kakashi's fathers death. In the gaiden (Kakashi 13) Minato explains that the mission which White Fang saved his comrades instead of proceeding with the mission was 5 years earlier (Kakashi 8). This coincides with Kakashi slow down in progress remember he graduated at 5 and became Chunin at 6 after the second ninja wars when tensions were still high (third ninja war broke out only four years after second ended) so they may have needed more shinobi quickly but it may also be because of was what his father taught him as he was much younger than other genii to graduate (minato graduated at an older age during a war) so with his father no longer there he may not have become nearly as strong. Without his father he also would have most likely not been able to learn any more family jutsu (special uses of white chakra blade) or have proper contact with any more summoning creatures.
Wondering what other people thought who probably have more of an idea than me?
Him seeming weak to me just may be the need of progression of the story and while Naruto needs to progress super quickly Kakashi does not and him being a genius at a young age may be needed. I think fights that do not seem massive now drained Kakashi heaps.
Sorry for the shortness of sharingan Kakashi part but you have all seen his strengths in the manga/anime