This is probably the best and most powerful Dua because it asks for the best in this world as well as in the hereafter! "Rabbana atina fid dunya hasanatan wa fil Aakhirati hasanatan waqina ‘adhaban-nar"
Best Dua for glorifying ALLAH - "Subhana Allah wa bihamdihi adada khalqihi wa rida nafsihi wa zinata arshihi wa midada kalimatihi."
Best Dua for forgiveness - "Allahumma anta rabbi la ilaha illa anta khalaqtani wa an abduk wa ana ala ahdika wa wa’dika ma istata’tu, a’udhu bika min sharri ma sana’tu, abou’ laka bi ni’matika alaya, wa abou’u bi dhanbi, fa-ghfir li, fa innahu la yaghfiru dhunuba illa anta."
“The most superior way of asking for forgiveness from Allah is: “O Allah! You are my Lord. None has the right to be worshiped except You. You created me and I am your servant and I abide by your covenant and promise as best I can. I seek refuge in you from the evil, which I have committed. I acknowledge your favor upon me and I knowledge my sins, so forgive me, for verily none can forgive sin except you.” If somebody recites this invocation during the night, and if he should die then, he will go to Paradise (or he will be from the people of Paradise). And if he recites it in the morning, and if he should die on the same day, he will have the same fate.” (Al-Bukhari)
Best Dua for protection - "Bismi Allah alladhi la yadorru ma’a ismihi shay’ fil ardi wala fi sama’ wa huwa sami’u al alim." The Prophet Mohammed (peace be upon him) said - "He who recites three times every morning and evening: ‘In the Name of Allah with Whose Name there is protection against every kind of harm in the earth or in the heaven, and He is the All-Hearing and All- Knowing,’ nothing will harm him. (Abu Dawud and At- Tirmidhi)
Best Dua for depression - "La ilaha illa anta subhanaka inni kuntu mina adhalimeen."
“The supplication of Dhun-Nun (Prophet Yunus) when he supplicated, while in the belly of the whale was: ‘There is none worthy of worship except You, Glory to You, Indeed, I have been of the transgressors. So indeed, no Muslim man supplicates with it for anything, ever, except Allah responds to him.” (At-Tirmidhi)
Best Dua for inner peace - "La hawla wa la quwwata illa bi Allah al ‘aliyyi al adhim."
Abu Musa (May Allah be pleased with him) reported: The Messenger of Allah said to me: “Shall I not guide you to a treasure from the treasures of Jannah?” I said: “Yes, O Messenger of Allah!” Thereupon he (peace be upon him) said: (Recite) ‘La hawla wa la quwwata illa billah‘ (There is no change of a condition nor power except by Allah). (Al-Bukhari and Muslim)
Ayat al Kursi - "Āyat al-Kursī is the greatest verse of the Qur'ān. This is because the verse beautifully describes who Allah is. The most majestic verses in the Qur'ān are the verses that talk about Allah, as there is no topic of discussion which is more grandiose, more majestic and more beautiful than Allah (ʿazza wa jall)."
This is Ayat ul Kursi - "Allāhu lā ilāha illā huw, al-ḥayyul-qayyụm, lā ta`khużuhụ sinatuw wa lā na`ụm, lahụ mā fis-samāwāti wa mā fil-arḍ, man żallażī yasyfa'u 'indahū illā bi`iżnih, ya'lamu mā baina aidīhim wa mā khalfahum, wa lā yuḥīṭụna bisyai`im min 'ilmihī illā bimā syā`, wasi'a kursiyyuhus-samāwāti wal-arḍ, wa lā ya`ụduhụ ḥifẓuhumā, wa huwal-'aliyyul-'aẓīm." Its meaning in English is - "Allah - there is no deity except Him, the Ever-Living, the Sustainer of [all] existence. Neither drowsiness overtakes Him nor sleep. To Him belongs whatever is in the heavens and whatever is on the earth. Who is it that can intercede with Him except by His permission? He knows what is [presently] before them and what will be after them, and they encompass not a thing of His knowledge except for what He wills. His Kursi extends over the heavens and the earth, and their preservation tires Him not. And He is the Most High, the Most Great."