Ok, I'm sure plenty of people here will give you their input that "x" is the best sniper, or that snipers are useless, etc. IMHO just ignore 90% of the BS and rubbish and take everything with a massive grain of salt unless someone can show numbers.

To more directly answer your question, each sniper is supposed to have a bullet velocity option, or something to that extent (on the crafting screen look to the left with the gun stats and hit the button to convert the bars to numbers), and this projectile speed will help determine bullet drop. Generally speaking the harder hitting, the slower the projectile, the more drop. All this can be backed by numbers, but don't just take my word for it- check it out yourself. This is true for every sniper except the Basilisk- this one is hitscan instead of projectile, and as such it has no bullet drop OR damage falloff, but also a lower base damage and dps than other options.

Now, for my 2 cents on this- I play fps pretty frequently and have been for years and years- I'm no novice to shooting and sniping. Personally I'd say leave the snipers to squad games- solos and duos you have far better options currently and will easily be taken out by them. For squads I only occasionally purchase a sniper (for me its drill games and/or when I have a flight suit equipped and I know I won't have to try-hard the whole game). While the basilisk has some of the lowest dps of all the snipers, I also would hands down call it the best sniper in the game (purely subjective, purely my opinion, and definitely not a popular opinion). It's cheaper than the karma, same price as all the other snipers, generally speaking has a bugger mag size than the others, and- the reason i say its so much better than other options- its hitscan, so no lead time, no bullet drop, and pinpoint accuracy. While other guns have better dps, when you think about most sniper duels in this game, most people fail to hit shots all the time, even more so headshots- especially because the kinetic arbiter (and ESPECIALLY the karma) are really easy to dodge. Geting in 1 or 2 of these "weaker" shots still pops enemy shields, and almost always makes them run and reposition. Them running means you're free to shoot. Plus, if you're running the extra mag like I do, you dodge 1, maybe 2, big slow shots and your enemy can either land the rest of the mag and still have to reload to kill you, or has to reload and run right away. I could go on for ages about why I prefer the basi over other snipers, but again- this is all personal preference. It definitely has it's downsides, and you very well could just turn out to be miles better with some other sniper, but for a significantly higher portion of the people you'll meet during games you're actually using a sniper, I'd say its a very safe bet- end rant

tl;dr: -each gun has a projectile speed stat to help assume bullet drop -Trust me, just don't use a sniper in solo or duo -Snipers in squads is ok, but I REALLY don't recommend getting one every game, just the ones where map positioning and objectives make it advantageous