Be careful asking for and listening to opinions on something that is a factual topic... not all opinions are formulated on accurate input/information or made after thorough research...
GE I silicone adheres to glass better than GE II... compare the packaging for verification on that one...
There is a rumor which appears to be true, that All Glass used GE I Silicone to make their tanks and they repackaged it and sold it under their own label for an exaggerated price.
GE lists their silicone as "not safe for aquariums" to avoid liability, yet it is likely not every customer service representative is aware of that and the ones who are surely wouldn't admit it to a caller.
GE (and most if not all other brands) use an ammonia based additive in their kitchen and bath silicones. The 'bioseal' contained by GE II is NOT the same ammonia based additive.
GE I and GE II use different curing methods/agents. GE I releases harsher chemicals during curing which is why they developed GE II. But GE I is a superior product which is why both remain on the market. The curing method of GE II leaves the product somewhat mold/mildew resistent, which is why it is listed as "bioseal'.
100% silicone does not mean 100% silicone. It means there are no other pastes, glues, adhesives, etc contained. They are still allowed to add coloring agents, mold/mildew inhibitors, curing agents, etc, etc, etc and still list it as 100% silicone. If not how would they change the color?
There is at least one ingredient in GE II that has been proven to have adverse effects on the reproductive process in animals. It is commonly suspected that this ingredient is in such small quantities that the effect is null.
In conclusion, I suggest using GE I over GE II... but if you want/need colored silicone GE II can be used...
For the record, DAP Plus series is very comparable to GE II and DAP (non plus) is very coparable to GE I...
In my opinion, the high dollar aquarium silicone is a marketing ploy and the educated consumer should not be fooled into thinking they need to pay the extra money for it.