As of now the best Prime Minister candidate, no doubt, is Sri. Narendra Modi only.  This is a pure evaluation of merits and expectations based on the till now the performance of him as Gujarat CM and as Prime Minister of India. This is written with a disclaimer that no one should revert to me on this matter after the actual election results in any way, whatever the outcome. As Gujarat CM he has developed the state to be a model to be emulated. Other than the die-hard critics, all leaders and economists and ordinary people have admitted and appreciated Modi's tireless work and devotion to the development of this country. The central government under PM Modi and the highly qualified and able Ministers have done, within a short period of seven to eight years, more than what the previous Congress governments for many decades could not do.
Modi's long-term vision
Modi is doing things with a long-term vision of how India will be in the next decades and the next century also. He is taking efforts to make India a developed power as early as possible. As PM of India now Modi is the most popular leader in the world. His popularity has shadowed even the President of the US. His rapport with world leaders and his image as a tough nut to crack and his impeccable history as a non-corrupt and 'non-saleable' political leader has made his position very strong in the eyes of world watchers and influencers. For the same reason, he has enemies and vested interests working against him and trying to malign him with false propaganda. We can easily assume that even developed countries and China have expressed secret jealousy against him and our nation's growth because by his tireless and dedicated India-centric programmes he exposed the foxy multinational businesses and Western political powers.
Modi's international popularity
Whatever country he visits, he gets a frenzy audience from the Indian diaspora- unparalleled in date history given to the leader of any country. I thus think that there is no other known political leader now in India who can work for India with a long-term vision of making this country NOT ONLY a developed nation but a world leader and World Guru. There is no other known political leader now who is non-corrupt there is no other known political leader now who works for long hours every day, three hundred and sixty-five days a year without even a day's holiday. There is no other known political leader now who ignores the venom spit against him but works for the nation using that time too. There is no other political leader now in India who could accomplish so much within a short time doing good to people and the nation. There is no other known political leader now in the country who gave moral courage and material to the armed forces, who stuck at the chest of the inimical terrorist century and warned them to desist from misadventures against this country.
The achievement and accomplishment of India in Digital transactions is an example and model to the world. That is just one example of Modiji's leadership, commitment and Vision. The infrastructure development in the transport sector all around-on road, rail, water and sky -is also unparalleled and exemplary even to other nations. I can go on and on in this regard.  Now the readers can compare the works of any other leader he knows and see that Modi excels in all of them and what I have said above is just a speck of what are all the real work and achievements by Modi as Prime Minister of India. Hence Modi stands as the best Prime Ministerial candidate for the next general elections.
Seeing the overall performance of the present regime under Mr Modi, I also have an opinion that he would again emerge as a winner in the 2024 elections and will be PM for a third term in continuation.
There have been many reforms and improvements during the last 9 years and more are on the anvil. The general public has a feeling that he is taking a lot of actions and initiatives for the development of the country and the whole world is taking note of it. During the last few years, there has been a very good improvement in infrastructure and other facilities in the country.