M4A1: 30-20 damage, 725 rpm, 1.12s partial reload, 2.4s full reload
FAMAS: 40-30 damage, 428 rpm (.32s between bursts), 2.2s/2.6s reload
SCAR-H: 40-30 damage, 566 rpm, 1.8s/2.72s reload
TAR-21: 40-30 damage, 725 rpm, 1.72s/3.094s reload
FAL: 50-35 damage, 508 rpm, 1.84s/3.381s reload
M16A4: 40-30 damage, 468 rpm (.28s between bursts), 1.12s/2.447s reload
ACR: 30-20 damage, 737 rpm, 1.12s/2.365s reload
F2000: 30-20 damage, 900 rpm, 2.08s/3.464 reload
AK-47: 40-30 damage, 634 rpm, 1.8s/3.305s reload
All weapons have a 1.4x damage multiplier for headshots except the FAL, which has 1.5x for a headshot and 1.1x for a neck shot. Snipers also use different multipliers. And of course there are a lot of other considerations when choosing a weapon other than damage, fire rate, and reload time. Iron sights vary a lot, magazine capacity varies, and some weapons have a lot less recoil, like the ACR. I don't know what the exact cutoff is for short vs. long range.
Far as I can tell, the TAR could be considered the best one on paper... it has the higher damage numbers but is still full auto, and unlike the SCAR it has 30 rounds per magazine instead of 20. It also fires and reloads faster than the AK-47. But the TAR's sights are not very good and the recoil is kind of high. The TAR's red dot sight is pretty bad too (the MARS sight, which seems to restrict your view more than a normal RDS).
MP5K: 40-20 damage, 818 rpm, 1.8s/3.08s reload
UMP45: 40-35 damage, 600 rpm, 2.04s/3.12s reload
Vector: 25-20 damage, 900 rpm, unknown reload
P90: 30-20 damage, 914 rpm, 1.8s/3.6s reload
Mini-Uzi: 30-20 damage, 923 rpm, 2.24s/3.56s reload
All SMGs take 0.24s to aim down the sights.
L86 LSW: 40 damage, 725 rpm, unknown reload
RPD: 40 damage, 627 rpm, 7.2s/9.744s reload
MG4: 30 damage, 725 rpm, unknown reload
AUG HBAR: 40 damage, 617 rpm, 2.44s/4.047s reload
M240: 40 damage, 898 rpm, 5.04s/7.823s reload
LMGs do not have any range penalty. They all take 0.44s to aim. Adding a silencer reduces damage by 10.
Intervention: 1.5x-1.5x-1.1x, 0.92s/1.966s reload
Barrett .50 cal: 1.5x-1.5x-1.1x, 2.6s/4.086s reload
WA2000: 1.5x-1.5x-1x, 2.56s/3.984s reload
M21 EBR: 1.5x-1.1x-1x, 2.08s/3.704s reload
Sniper rifles all take 0.44s to aim. They all do the same damage (70, or 50 when silenced), and the numbers represent multipliers for head, chest/neck, and body/stomach shots.
PP2000: 40-20 damage, 833 rpm, 1.28s/2.02s reload
G18: 30-20 damage, 818 rpm, 1.88s/2.835s reload
M93 Raffica: 40-20 damage, 454 rpm (.32s between bursts), 1.4s/3.03s reload
TMP: 30-20 damage, 865 rpm, 1.2s/2.539s reload
All machine pistols take 0.2s to aim. Shotguns also take 0.2s to aim, but there isn't much other data on them.
USP .45: 40-25 damage, 1.36s/2.319s reload
.44 Magnum: 50-35 damage, 1.48s/3.074s reload
M9: 40-30 damage, 1.24s/1.966s reload
Desert Eagle: 50-30 damage, 1.48s/2.165s reload
All pistols take either .16 or .2s to aim. They aren't clear on that, but the difference is tiny.
Also, all weapons equipped with the ACOG scope take 0.44s to aim, even SMGs.