Battle strength(think 1v1 scenarios)
1Naruto
2Hashi
3Tobirama/Minato
4Hiruzen
5Tsunade
(in terms of battle strength)
The reason that i put Minato over Hiruzen, is because We have not seen a prime hiruzen, so i cannot say he is stronger. I Was really debateing putting tobirama with hiruzen, but i decided tobirama was just a bit better.
Now in terms of usefulness, as a hokage, not in fighting strength,
1Naruto
2Tsunade
3Minato
4Hashirama
5Tobirama/Hiruzen
Naruto is number 1 because he is able to help the most. He can cloak the entire village with chakra cloaks, which protect them and enhance their power,(also maybe heal them somewhat?) also he can make tons of clones that are jonin strength each, and send them to each battle field. With BM he can deal with large threats as well.
Tsunade can tank and heal an entire village while they are under attack, useing katsuya. She is good at makeing decisions, and an expert at healing people. She may not have a ton of offensive power, but she has a ton of supporting power. Also she is extremely hard to kill in a fight. I chose minato as second because he can ftg to multiple locations to help out with fights. He is very quick, and can save people with ftg. Also he can ftg big threats out of the village(like nine tails). The reason he is second is because he is fast mobile and precise in his strikes. Hashirama is just barely above Tobirama and Hiruzen, because he has a very charismatic attitude, and he has a ton of raw power. Also he can make a large number of clones to help people fight off intruders. He can easily take care of large threats. He is not above minato, as he cannot move nearly as fast, and is not as precise as minato is.
Tobirama and Hiruzen, have not been shown to have large clone feats, massive healing techniques, or precise strikes. However they are still strong fighters 1v1, and both are strong. But they seem to bring the least in terms of support to the village.
(btw what i mean by support to the village is like if the village is attacked, and or at war. again not a indicator of raw strength(think oro invasion/pain attack(not neccesarily people that strong as the leader though)
Lastly my final list, chakra levels.
1Naruto
2Hashirama
3Tsunade
4Tobirama
5Minato/Hiruzen
I think naruto has higher chakra levels with the 9tails than hashirama, but who knows. Naruto without kurama is probably tsunade level chakra. Tobirama is a strong senju so i put him 3rd, and minato and hiruzens chakra level is unclear. They are not senju, so i give tobirama benefit of the doubt.
So now is the overall rankings
Naruto 1+1+1=3
Tsunade 5+2+3=10
Minato 4+3+5=11
Hiruzen 4+5+5=14
Tobirama 3+5+4=12
Hashirama 2+4+2=8
So the above is adding their rankings to give them an overall ranking. Keep in mind that all the stats are based on war/ fighting bits. Leadership is not included, and neither is intelligence etc.
#1 Naruto
#2 Hashirama
#3 Tsunade
#4 Minato
#5 Tobirama
#6 Hiruzen.
A brief recap so i dont get flamed... Naruto has the largest chakra reserves with kurama. He also has great support abilities. Lastly he is a strong fighter. Since naruto has yet to 1v1 a person with a fully charged kurama, i think he would be as strong as hashi or close to his power. Naruto has not been able to train useing kurama powers very long, and has been fighting a war. All of this combined gives naruto a overall ranking of #1.
Hashi is second, because he has strong fighting abilities, and large chakra pool.
Tsunade is 3rd because of her chakra pool and support ability
Minato is 4th because his support ability as a precise strike, and the ability to jump to mulitple battlefields. He is average at battle strength and chakra pool.(i did not count minato kcm btw). He is average overall.
Tobirama is 5th because of larger chakra pool than hiruzen, and slightly better fighting strength than hiruzen.
Hiruzen is last, because he has not shown large chakra pools like the senjus(tobirama hashirama and tsunade) and naruto.
He has among the least ability as a support, and has not shown to be an incredible fighter. He would possibly be ranked above tobirama, but since we have not seen a prime, i cannot fairly rank him higher as a fighter.