Everybody prefers something over something else. In that case, that's among the three sun-producers in PvZ 2. Others prefer the original Sunflower, others prefer Sun Shroom and others prefer Twin Sunflower.
But others were also arguing which one is the best. 75 Sun. Cheaper, economical, more, double and many others. Not angry, though. I just wanna type before it gets forgotten.
So here are the three.
First obtained. It's a simple sun producer with no or less hassle. Goes with a simple pay-and-plant concept: needs 50 sun and likewise it gives 50 sun. Simple.
Its simplicity sometimes shadows its potentials. It only produces 50 sun unlike the other two, with 75 and 100 sun. To generate more sun, one needs planting more (quite obvious though), which may consume spaces needed for certain strategies.
25 sun cheaper than a Sunflower, making it easy to plant, especially in Dark Ages. One can get two Sun shrooms instead of one sunflower. It is favored because it grows and produces more sun: which both flowers are not capable of. 75 sun has a great potential for planting more costly plants. When it grows, it will leave some net amount of sun
Despite being easy to plant, it still produces less sun in its first stage. One must wait to let them grow. Defenses may be easily overrun at first because 25-50 sun may not be enough for plants costing 200 sun or higher. This is common in high levels of Endless Zones.
Produces 100 sun compared to the former two. Favored because it is a space saver. Why plant two Sunflowers if one can afford planting this, with only one space? Two columns of this generate 1000 sun (theoretically speaking, if they would at the same time).
Unlike the first two, the sun generated by this does not pay for itself. It'll leave a debt of 25 sun when it is planted and generates sun (however, falling sun during day compensates for this). Similarly to Sun-shroom, it will take a while before some equilibrium and balance can be achieved. Its recharge is mediocre so planting won't be as fast as the aforementioned ones.
The observations mentioned here assume normal gameplay. Also, these do not count the use of plant food. Plant whatever you want to plant. Whatever you choose among these three, go for it. Just like all plants, players also have a unique strategy to come up with.