>>96184008
The most important things to consider when picking a legion:
>Do you like their lore?
>Can you see yourself painting the colour scheme?
>Is their preferred style of warfare something you like to play?
I landed on Alpha Legion because I really liked their duality of being masters of infiltration and spec ops, but at the same time so thirsty for recognition that they want to style on their enemies during a final fight.
Having played 40k for a long time my preferred play style ended up being MSU with multiple back ups and redundancies, which works very well with the AL rules in all editions so far.
And I like the most common AL colours too, so painting was fun as well.