I am going compare the
H2O cart and atty vs Joye 510 mega atty and cart, using my Tornado.
The carts have been renamed by me as the "little beast"....I counted 24 drops....and I did read where someone only got 19 drops and the H2O web sight states 23.....our bottles must be different sizes.
The stock filler is better quality than the megas. I really enjoy the carts due to the fact it holds more than the mega carts, and when you top, your juice flows very evenly throughout the stock filler. I love that these carts have not "sweated" on the outside at all. If I am in a car, and I pull out the cart to refill, I hate that the juice "condensation" clings to the outside of the 510 carts, the H2O carts do not have that issue so far. No sticky fingers! Another huge bonus with me was the fact I left yesterday for a few hours and all I took was my Tornado with the H2O cart and atty. No juice to keep up with. So, one less thing to drag around. I vaped throughout the 2 hours with juice remaining when I returned home.

I use the blue foam filler with my 510 mega carts, I don't even bother with the mega stock fillers, I throw them away. Given a choice, and which I was this morning, when I left the house, I chose to use H2O cart, stock filler and atty over the mega accessories. The draw is so much lighter for me, the air flow is very smooth, like drawing on an analog, whereas with the megas, it is a harder draw...which I now dislike after trying H2Os.
H2O states the carts are great for dripping, they need too also state they they are excellent for non-drippers as well!
So, 10 of the H2O carts will run 11.98 vs the megas at 12.99...not much of a difference in price, just a preference for me, I will be getting more of the H2O "little beast" carts.
I tested the atty before use, my digital meter read at 2.2. I did not taste the bitter primer, all I did was the normal "blow it out" routine, added the filled cart, I did not add any drops of juice to the new atty, the results were excellent, I did not have a disgusting taste like I do with the others. The juice tasted perfect from the first draw on. I really enjoy the attys as much as the carts. They wick very well and steady. The H2O carts do fit on my regular Joye 510 atty, although it is a tight but secure fit.
I get plenty of TH and plumes of vapor. I hesitate saying that because I believe that part is subjective for many reasons, one of those being the juice your using. But, so far, I have used 4 different type juices, and so far, the H2O atty and cart has delivered as described, maybe better. In case your interested, the juices were coffee, menthol, peach and a tobacco.
I can get a H20 atty for 14.99, with a stated one warranty vs a mega atty for 17.99 with a 28 day warranty. Didn't take long too figure the math here. I will add more H2O attys to my stock as well.
The other atty in my OP is not the same as the H2O atty. The other atty must be a SLB because it is definitely not a H2O or Joye.
Those who claimed that the H2O atty is the SLB atty, compare yourself:
H2O atty on the left and the SLB atty on the right:
Since the atty and carts are new, I will post a follow up.