they all work the same, i am never too picky. The slime coat stuff just means there will be a little extra bioload...
Sadly, they do not all work the same.
The "extra bioload" may or may not be true dependent on the brand. The real issue with the so-called "slime coat additives" is that these products are designed for fish. Amphibians are not fish.

Often, these additives are nothing more than high concentration sodium chloride and aloe extract suspension. In the case of Prime and NovAqua in particular I noticed that the resulting irritation did in fact develop an undesired slimy reaction with larval and neotenic caudates when used as directed on the label.
Ever notice the number of posts about (in particular axolotls) and questions involving something like "OMG shedding!" or "White slimy stuff on gills!?!!?!" or "Goop?"? I would feel safe in stating that a good portion of these are direct result of the improper/over use of products designed for fish that include these additives. (coupled with husbandry practices)
I too had all sorts of issues with strange white sludge, wild variation pH, and ammonia spikes and gill fillembrial loss until I dumped using all of those products and zeroed in, through trial and error on the strictly sodium thiosulfate in solution products. By eliminating use of the products utilizing those additives all of those issues stopped for me even though it took years of trial and error.
Normally, I would back such claims up with hard data, research, or a mad scientist experiment, however I am unequipped to prove or disprove such theories at this time. Just over the last few months have I gained the knowledge to explain how and why the Amquel+ works as it does. Even so I do not feel comfortable enough in my knowledge with the subject to properly and quantitatively explain it.
Therefor I must rely strictly on personal observation and personal anecdotes at this time.
Truthfully, I am of the opinion that local off the tap water chemistry also plays a big role in proper selection. With the little bit of research I have done on the subject, I suspect that potable water standards vary wildly in North America as there is no real national uniform standard for many aspects of chemistry. Carbonate hardness standards are non-existant and treatment methods(use of chlorine, chloramine, flourides, bromides, etc) in particular vary wildly here, unlike in Australia.