I use Germall Plus, why? well for many reasons.
It gives products a great shelf life, I forget exactly but it would be easy to find from the supplier or producer, many preservatives are broad spectrum/anit fungal/anti bactericide, but many do not last as long, which Germal Plus is a broad spectrum as well.
It is Paraben free!!! This is not just a new hype or fad, it is fact that Parabens are very very bad. Orgin toxicity, etc etc. I do not use anything with Parabens from all the things I understand about Parabens, there is oodles of info on Parabens.
Many "natural" preservatives are still considered unhealthy or toxic. Mercury is natural, but bad! Arsenic is considered natural but deadly! Cyanide is a natural, but bad, you get the idea.
Some preservatives can be irritating to skin tissue, like potassium sorbate which has a high irritation rate, and is not broad spectrumand very PH sensitive.
Some preservatives have consequences like PH drift, discolouration etc etc. What good is a naturally preserved lotion that has turned to cottage cheese because of destabalization.
Germall Plus is a formaldehyde donor, which means it provides an element needed to produce formaldehyde which acts as a preservative. This said, our body's produce formaldehyde everyday which we excreate through urine. Used appropriatly it posses little risk. Yes it is toxic in high doses, but our systems can easily deal with the amounts in lotions, I would be more worried about eating McDonalds, sorry to the McD lovers.
I am interested in switching to a more "healthier", "natural" preservative myself, I just have not figured one out yet, my idea so far is to mix Leucidal, aspen bark extract, and elderbarry extract togehter to get a "supper" natural preservative.
The most important thing I can say on the matter! I have only tried Germall Plus, and Opthiphen Plus. My choice and understanding is from what I have gathered throughout my searches. I'm just sharing my thoughts on the matter, no facts. Its all a matter of personal preferences.