Best day of my life right now
I just began watching the Accelerator iteration of the series because it was the shortest of the 3.
I am well aware Railgun is more popular and appears to be the foundation for the other 2 series, however the Accelerator character is voiced by Bakugo so he wins my attention by default. Though I still loath him as Garfiel in Re: Zero.
I will probably watch Railgun second and then Magical Index last.
If this is like Haruhi Suzumiya and there is a set order to watch the episodes let me know.
So far I am only 2 episodes into Accelerator.