This is my own ranking from the best to the worst plant.
1. Winter Melon: The best plant ever! Strong, efficient, and an awesome PF ability.
2. Melon-pult: Same as WM, but the freezing effect gives Winter the first place.
3. Power Lily. The best premium plant so far. It gives a good support to all plants.
4.Sun Shroom. Triunfal reappearence! It defeats Twin Sunflower at everything. Cheaper, better sun production, and a good PF ability. Has one of the worst costumes, through.
5. Kernel-pult. It's PF effect gives it the fifth place. The only way to beat an AC level with Wizards and DA Gargantuars.
6. Cabbage-pult. Cheap, efficient and it's PF effect can save me from Jesters and Wizards.
7. Cherry Bomb. A huge wave of zombies? Your lawn is full of that annoying Gargantuars? A Cherry Bomb is the answer to all your problems.
8. Laser Bean. The perfect partner for Winter Melon. He can deal with a lot of zombies at a time. The best Far Future plant.
9. Fume Shroom. A cheaper LB, if you don't have a high amount of Sun, he is the alternative choice.
10. Wall-nut. Why I put Wall-nut instead of Tall-nut? Two words: Sun cost. If cheaper, better.
11. Puff Shroom. When someone says OP, you always think of the Puff Shroom. The only bad think about him is the fact that he disappears in 60 seconds.
12. Iceberg Lettuce. Meanwhile you are saving suns, Iceberg can freezes zombies, saving some time. Also, it's a good complement having it boosted.
13. Blover. A lot of Jetpack Zombies and Bug Bot Imps can make you lose, so here's when Blover comes in handy. Also, if there is a PF boosted Spring Bean, even better.
14. Imitater. A good use for the Imitater: always imitate your boosted plants, especially Puff Shroom.
15. Magnifying Grass. I don't know why you hate it. If there's a good amount of Sun Shrooms, Magnifying Grass becomes one of the most powerful plants.
16. Sun Bean. If boosted, you can replace Sun Shroom or Twin Sunflower with him. Give it to zombies with a high amount of health, like the Robo-Cone and the Knight.
17. Snapdragon. Cheap and strong, but it can religth the Explorer Zombie's torch, so be careful.
18. Twin Sunflower. It was nerfed on the last update. Sun Shroom it's better.
19. Potato Mine. Good: Cheap, efficient and saves time. But, since Puff Shroom arrived, was replaced.
20. Tile Turnip. It can make every level a piece of cake. The only bad think about him: it's price.
21. Pea Pod. I don't like peashooting plants, but Pea Pod is an exception to this.
22. Bonk Choy. He has a good PF ability, but it's a plant that cannot control a crowd of zombies, unless boosted.
23. Magnet Shroom. He is good in the normal levels, but later it will become kinda useless due to the high presence of the Zombie King.
24. Spikerock. Sometimes is useful, mainly with freezing plants. But I don't use it always.
25. Jalapeno. When you need to take care of an unprotected line, Jalapeno is your best option, but the Cherry Bomb can replace it.
26. Spring Bean. If Blover wouldn't reappeared, it will be the last place. Also, a cheap way to kill the Pirate Gargantuar.