Re: Personal ranking of every interpretation of non boss plant npcs.

It''s been too quiet around here lately and I wish they hadn't removed the separate GW2 forum, but we will make what we have work. I love seeing posts like this @stukapooka , I'll be a little more general in my reply and not tier them up like you have, although they certainly have their tiers, and I can't really disagree with yours, barring a few spots that I'll mention in my summary.

Weeds: The basic weed was never great for summons in GW2 thanks to their low health. And I mostly summoned them just because we have so many there, and to get the summon AI quests done. 

Dandelions: Like the zombie counterpart, the Imp (summonable version), these aren't great when used singly. The type summoned by the Wildflower character are far better since they can be manually steered and given buffs on top of that, but the swarm characters are problems for many reasons. 

Pumpkin Weeds: Minor upgrade to the base weed, but that works out considering how common these are in GW2. I may have more of these than the base weed in fact. When a bunch show up in place of, or in addition to, the basic weeds in Ops, they are far more effective as the extra health scales up rapidly.

Feastivus Weeds: Not much to add here. I have a bunch as I buy some every year, but don't use them much since they are still limited. 

Leaf Shield Weeds: These guys are decent and add a bit of challenge to Ops and BfN free roam regions. Far better than the basic weeds although vulnerable to flanking.

Hypnoshrooms: Are obnoxious to fight, although far worse in BfN where a bug leaves their hypno effect to linger for a significant time after they're vanquished. I do enjoy them being in the game overall and love their vocalizations and hopping gait.

Terracotta Weeds: Significantly more powerful than the basic weed and even the pumpkin weed. No special defenses to make them too strong but can soak a fair amount of punishment. Nasty when in groups like the terracotta waves in graveyard ops.

Dreadroots: Can be extremely obnoxious when you're just trying to explore and you end up with 3 of them. Once you can play the lullaby tape I would do so often when I was trying to 100% Weirding Woods. Their tendency to submerge often makes them frustrating to deal with, but they are one of the more interesting enemies to fight as well.

Wildflowers: I really don't like these guys at all. It's rare I complain about them adding more stuff in the PvZ universe, but this is one of those times. They break the balance between hordes of mostly melee AI supported by players or rarer, higher level AI enemies, and the defenses that already have some problems (especially in BfN). They are likely too effective and even with their lower health I'd put them at at least a B since they can shoot and cause you to miss with their bloom boom ability.

Vase Weeds: I definitely rank the GW2 version higher than the BfN version as you point out the cooldown is very long in BfN. I still feel that the idea behind cool down timers for summons in BfN wasn't a bad idea since it eliminates the spam of GW and GW2 of only the better stuff, but the lack of variety and cooldown timers that are this long made the system less palatable than it could have otherwise been. Their exposed eyes and to a lesser extent, their roots, are vulnerable, which makes them easy targets when isolated but they are often caught up in heavy combat with other targets which makes careful aiming to hit those spots more difficult.

Heal Weeds: Don't see them too often in multiplayer matches as they aren't that common in GW2 packs, and have a significant cool down in BfN, but I do see them more often in BfN. I've used them at times in GW2 to give me a little extra heal as a Sunflower or just to help out at times. One of the better summonable plants to be sure, but also best used in moderation, often in combination with more aggressive plants. The ones that automatically spawn in the backyard in GW2 are extremely handy when you want to fight some bosses in a big battle. They love to hang with you in the backyard too, much like the flag zombies.

Terracotta Wildflowers: Annoying made worse with extra health. Again, I normally love to see how creative the devs can be, and BfN does have some stuff I like, but these guys are just more powerful wildflowers, so more of something that breaks the balance. Very effective when they are part of an attack with players in TT.

Wood Shield Weeds: Solid guys as they're even tougher than their leaf wielding counterparts. One of my favorites to summon in GW2 when I need summons that have a bit extra survivability.

Flag Weeds: Not much to add here. Great guys when lots of plants are nearby. With the AI for summoned weeds (and zombies for that matter), meant that they would seek each other out as best they could for a coordinated attack to take better advantage of the flag and heal AI.

Porcelain Vase Weeds: Better vase weeds with a more elaborate pattern on their vase, so not much to add here.