As we ak know fallout 4 will likely take place in the Commonwealth so heres what i think the factions should wear.

The railroad, they should wear worn down brown trench coats
The Synch Retention bureu should wear leather black trench coats,like in blade runner
While the regular Commonwealth police should wear blue combat armour...

And if the MW Bos appear keep their armour the same it looks very cool.

Please use the http://www.gamesas.com/index.php?/topic/1164088-fallout-4-speculations-and-suggestions/, thanks