I tend to select a different setup based on what level I'm playing and which characters are in my team.
Harec is very stealthy, as Ebisu_rkz says, but when you shoot with Vindicta Anima your stress increases and you are exposed. While this might not seem like an issue, the AI can pick on you or even the Antagonist/Raider can spot you after a shot. I tend to default to it when I'm not sure what to select.
Aura Mortis won't expose you on shoot, which is great, but in turn it takes longer to charge than Vindicta Anima. It also has a higher max charge and it doesn't decay after it is reached, so you could stay aiming until you find the shot you're looking for. Be careful, though, as you will be missing a lot of the action around you while aiming (this applies to all of these weapons). I tend to use it when I'm playing solo or when I know my team are attracting all of the attention, as I use to be very separate from them and support them as they move or shooting down some mission objectives. The bad thing is that I run out ammo more frequently
Ignis Fugit is a very quick weapon compared with the others, which means you can deliver more shots in the same time span. However, it has a lower max charge and still exposes you on shoot. You don't have the same ability to one-headshot-kill everything, but it doesn't punish you as much when you fail a shot as with Aura Mortis. I'm still trying to get used to it, as I'm not a great sniper myself
Personally, I'd say they could be sorted based on how long range and how solitary you want to play. I'd say Ignis Fugit is a weapon that allows you to play in a shorter range because you can deliver faster shots even to players that are running to you; Vindicta Anima would be the most versatile; Aura Mortis would be the lone wolf, long range kind of weapon. But that's just my personal point of view! I'd like to know how you feel about it
As for the Cards... Again, I tend to adapt to the level, the team and the weapon in this case.
For Harec's Cards, I like Methodical, mainly when using Ignis Fugit, as it allows me to reload faster and deliver more shots. I tried Hieratic, Attrition, Favor and Habituation (they give you some benefits when you kill), but as I'm not a sharp shooter, I find myself performing more shots than kills
For the Alien cards, I'm used to Lone Hunter (I'm mostly in long range), Skill (extra reload speed) and Cautious (more damage the further away you are from the victim, specially useful with Aura Mortis for me).
I guess Concentration (more damage if you take long to shoot) works nice with Aura Mortis and Bold (more damage the closer you are to the victim) works nice with Ignis Fugit, but I haven't tested that build enough yet.
Wow, that was a long post! I hope my playstyle helps you find different setups
I'd want to know what builds you're testing too, so go on!