Least time spent on the floor
Are you looking to powerpass either Sharpshooter, Gunslinger or Shadowhunter. In general, assuming that they is played at the same level of skill Which one has a better time of not dying?
And if anyone can tell off their heads the cost, Shadowhunter aside, just what is the cost to construct?
If we assume the same skill level there's always the question of which level of skill we're talking about. I'm also going to assume more standard build types: Demonic Impulse for Shadowhunter, Peacemaker for Gunslinger; Sharpshooter's build isn't much different in this case.
Beginner/inexperienced player - Shadowhunter is by far tankiest and can heal up a bit with every transformation (demonic build), making her the most forgiving out of those three. Gunslinger is the squishiest, Lost ark gold and must deal with large animation locks, which makes her more likely to be in the floor position. Sharpshooter is a solid middle of these two.
Experienced/competent player (well known fight, few hundred hours of practice on class total) - Gunslinger has multiple mobility tools and very flexible range (can hit from melee to a screen away), letting you save spacebar cooldown to break animation locks and keep repositioning to stay safe. Shadowhunter is a melee-based class and heavily relies on the ability to land key skills in order to increase the meter of transformation, which can cause excessive risk/greed to hit a target and making minor mistakes (that can result in the loss of transform) which can be punishing. Sharpshooter is a second class is in the middle.
As as a Gunslinger you are able to play the game with a high degree of security and lose on dps only in windows in dps that you're missing (no resources are wasted and you don't have an identity bar, and cooldowns remain in effect until you've used them) Also, as a Shadowhunter you're limited in transform time to make maximum benefit from until you can return to stacking it. Hence, being too cautious can lead to a lower performance. however, Shadowhunter is more likely to suffer a fatality due to an error you make or a risk that is not worth it.
Cost: Gunslinger has 7 main damage-related skills, which means 7 damage gems and many tripods you'll need. Shadowhunter could make do using meter generation and cooldown tripods, as well as two gems in total, making Gunslinger substantially more costly.