I love burst-fire guns, mainly because they remind me of the Battle Rifle in Halo. So Burston Prime, Tiberon, and Sybaris have my vote for forma. Also, they are pretty great weapons for mid or long range firefights, even better at getting headshots with burst-fire guns than sniper rifles because snipers have weird scope designs and zoom in way too far for me in this game.
These are obviously not optimal builds for each weapon, but I've used them for a very long time and grew accustomed to them:
Burston Prime is like a status and AOE gun, due to the augment mod for it.
Sybaris is a crit-based burst-fire gun, but can only be fired 5 times before reloading. Fast hands (I don't have Primed Fast Hands) can be pretty helpful because you're going to be reloading constantly.
Tiberon is a raw damage burst-fire gun, but I still wouldn't add a Heavy Caliber on it. Fun Fact: "Tiburon" means Shark in Spanish.
If you noticed, I enjoy punch through mods and find them quite helpful but other players might disagree with me on that. So, replace Shred with a regular fire rate mod or Metal Auger with another elemental damage mod. Also, I don't really like Heavy Caliber with burst-fire guns because the scattering bullets can be detrimental when it comes to precision aiming and getting headshots.