All right. I did the math on every tower's DPS in order to create a comprehensive character guide, and came up with some... silly, results. Towers have been sorted by rarity, All values are calculated at level 1, 1 star, special abilities have been taken into account, but do NOT take into account varying upgrade rates, so Results May Vary.
Let's start with the basics.
Lin: 200 DPS.
Her special ability effectively grants her 1% of all other tower's DPS... but with such low base speed and damage, it's not enough to matter.
Ejira: 687.5 DPS.
No bells or whistles here, she's a pure damage dealer with no gimmicks.
Wendy: 60 DPS.
Don't be fooled: her ability causes 1000 DPS in an AOE around enemies should they die shortly after being shot, and it can stack with other Wendies or even herself if attack boosted. She utterly crushes Hordes, but cannot scratch bosses.
Evelite: 3 DPS.
She generates coins with her attacks at a rate of roughly 1 coin every three seconds she's firing on an enemy. Keep in mind that literally every price in this game rounds up to 10, so her income isn't as... appealing as it may first sound.
Lilith: 220 DPS single-target, 660 DPS multi-target, 880-2640 DPS when linked, unknown maximum potential.
Look. I know. You're staring at those last two values and loosing your fucking mind, but it's complicated. Lilith's basic attack hits the first three enemies at 1 star, meaning her DPS triples when facing hordes and not bosses. When two Liliths are in corners horizontally opposed from one another, they link, quadrupling their DPS. If all four corners have a Lilith in them, they boost further, though I have been unable to accurately measure this boost. Lilith is single-handedly the most batshit insane character in this game due to raw damage output when used correctly, but is one of like four characters that actually require skill to use, since you need to get them in the corners and KEEP them there, fuck that fucking randomizer boss I hate his guts.
Goullea: 350 DPS.
Her special effect causes slow to enemies she hits. This isn't that useful against hordes and can fuck Wendy over something fierce, but kneecaps bosses by giving you 45% more time to damage them.
Vivienne: 560 DPS.
Her special effect summons a free 1-star tower whenever you combine Viviennes, making her useful early-game for swarming the field. Her actual damage output isn't terrible either, so she isn't that big a burden after wave 20.
Eton: 0 DPS.
Her special effect applies a... stamina buff, to towers adjacent to her. It is unclear what this buff actually does, and we have a better character for that anyway...
Fidelia: 0 DPS.
Her special effect applies a 20% attack speed bonus to adjacent towers, making her effective DPS 20% of the four towers around her. An excellent force multiplier for most towers, and vital for breaking the glass ceiling that is waves 22-24.
Freya: 420 DPS alone, 555.45 DPS with a friend, 690.9 DPS as a threesome, 826.35 as an orgy, 961.8 as a harem.
Freyas boost each other's DPS by roughly 32% for each one adjacent, but... remember that Ejira can do the same by existing and Fidelia looses roughly 12% to be able to buff anyone. Outclassed by her competition, but one of the few skill-based characters, so eh?
Skatie: 60 DPS.
Hold on. Skatie's DPS might look low, but it's somewhat deceiving. Instead of shooting, she places mines on the track that stay there until someone steps on them, dealing 1200 damage to enemies in a small radius. That means she is always firing, even between waves, and her mines are GOING to hit someone eventually. While admittedly a burst damage DPS tower in a wave-based survival game, she can be useful for storing up damage to nuke a boss.
Sirlof: 0 DPS.
This one's wierd. Sirlof has no attack, and her special ability allows her to switch places with any character less then or equal to her star count (not Mirrors). This makes her solely useful for positioning the four towers that care about their placement, and while Fidelia, Eton, and Freya all appreciate her, Lilith LOVES this girl to death. No faster or more consistent way to light up the corners by wave 5 then Sirlof. However, as Sirlof doesn't actually do anything to help kill the enemy herself... strange, for a character wielding a sword, she is basically useless once the rubber hits the road, and simps so hard for the randomizer boss that she can throw runs single-handedly. Actually useless without one of her friends, and only viable with Lilith, but is at least more usable then... whatever Eton does.
Tania: 240 DPS + 360 for every enemy on the right side of the map.
Literally the only sword-wielder who actually uses her sword. Tania can put serious hurt on hordes, but bounces off bosses without impact. Her conditional damage output renders her generally less useful, but can rack up crazy numbers when the rubber hits the road. Though... she has significant trouble actually killing hordes herself, as the low firing rate of her special ability renders her vulnerable to being rushed.