In 'My Hero Academia' (MHA), it's challenging to nail down just who is the 'strongest' because it really depends on how you define 'strong'. If we're talking about raw power and destructiveness, then All Might in his prime would probably take the cake. His 'One for All' quirk could essentially level entire city blocks with a single punch. But if you think of 'strength' in terms of versatility and strategic usefulness, then maybe someone like Eraser Head (Aizawa) would come out on top. His 'Erasure' quirk can nullify others' abilities, which is incredibly flexible and has huge tactical value.
Then again, Endeavor's 'Hellflame' quirk, which lets him wield and manipulate fire, makes him an incredibly formidable hero as well. He's also the only hero who was able to sort of fill the void left by All Might. On the 'villain' side, Tomura Shigaraki's 'Decay' quirk is definitely one of the most dangerous in the MHA universe, he can disintegrate anything he touches with all five fingers. Last but not least, Deku, the protagonist, has immense potential with the 'One for All' quirk passed onto him by All Might, he's been shown to continually surpass his own limits.
So, while you can make a solid case for any of these characters being the 'strongest' depending on your perspective, my personal sentiment leans towards All Might. Representing the symbol of peace, he not only showcases brute strength but also the ability to influence and inspire others, which in my opinion, is a testament to true strength.