I just made the same comparison and went with the A51--not because I am an expert but because the the A51 had twice the RAM, longer battery life, much higher screen & camera resolutions than the iPhone SE.
From what I could tell, the only thing the iPhone SE had going for it is its brand appeal as an Apple device and perhaps more compact size--neither of which impresses me in the least.
It certainly could be that differences in the processor hardware could mean that the iPhone has better performance even with lower numbers; I did not have time to do a deep dive into that or reading a lot of reviews. So that is just my two cents' worth.
