I'll be honest, I'm a member of the Mandalorian Mercs Costume Club before a trooper, but both sides do have their downsides. Personally I chose to do a mando first merely because I liked them more. As well as the "mando-ing" aspect of custom paint jobs, it helped to get to do my first foray into costuming the way I wanted it to look.
And yes, there are members of the mercs that I sometimes wonder how they got in, or why a Hot Wheelsesque painted helmet is ok. And then there are people who look pretty mir'shebs in their beskar'gam.
But looking at the mercs CRLs and work done by the members, then looking at a few 501st Boba's whose coloring is not even the same green, it just made me want to do mandalorians justice jn my own way.
On te other hand I've always liked the stormies, the armor is awesome looking and the weapons are killer looking (even if they can't do jack squat with them) I just favor the idea that you get to choose your own paintjob, and make a backstory to go with every dent and scratch your merc had come across.
And truly never have liked the idea of trooping with a painted nerd gun. My current sidearm was a mixture of parts that I added together and gave a nice black paintjob to it. That way it has a more blaster feel.
Soooooo yeah, that's my take on the comparisson. Sorry for going against TKs to favor mandos, don't shoot me (not that stormtroopers could hit me. Sorry I tried to resist that I really did )