Self-explanatory. I will use a P unit to mark the scale.
Peashooter, one pea per second. 1P. Absorbs 6 bites, 7P. Plus 50P for price for 57P.
Snow Pea, technically slow down for 1/2, so 2P. Absorbs 6 bites, so 8P. For the plant boostage, 8 x 2 = 16P. +50P for price = 66P.
Repeater, just the same, 2P. Technically effective with Torchwood, plus 6 bites so 8P. Plus 2P = 16P + 2P = 18P for effectiveness. +40P for price = 58P.
Puff-shroom, 0 sun, for 60P. 1/2 damage per shot, so 60.5 DMG. Plus for the stall, 10P. For rounding, so 72P! Minus 5 for time durability, 67P.
Fume-shroom, 50P for price, 20P for control, 70P.
Torchwood, for the boostage, and control, 40P for price. 20 for control. 60P. For damage boost, 5P. 65P.
Starfruit, 5P for 5DMG, a total of 5x5 = 25 + 40P for price, equals 65P. For DMG, 5P, 70P.
Cabbage-pult, 57P for the editing on Peashooter, 10P for lobbing. 67P.
Melon-pult, 70P for damage, 20P for controls. Slowness, -20P. Total of 70P.
Winter Melon, 70P for editing on Melon-pult, with slowness making it twice effective + 10P for the additional splashes, so 90 + 10 = 100P! For it's -100 Sun discount, 115P.
Gloom-shroom, 50P for 4DMG + Control for 20P, 70P. for the range, 73P.
Gatling Pea, just 2x the Repeater -5P = 116 - 5 = 111P.
Pea Pod, for a hintisty of lower Butte/High west levels, you have 20P x 4 = 80P. -20 for price, 60P.
Bowling Bulb, for 3x8 multiply damage, for x2 for damage, 48P. (I like this plant, but he's losing) EDIT : Math accident, 69P.
Banana Launcher, does 60DMG per 21 seconds, easy to multi-use and cheap. +50P, so a total of 136P.
Banana Launcher wins.
2) Winter Melon
3) Gatling Pea (hate this plant but whatever.)
Torchwood don't deserve this rank.. but whatever.