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First, a primer on Frankincense and how the various varieties smell;Frankincense Sacra - this is basically the original frankincense from the middle east. The smell is fairly musty, woody, with a trailing note of citrus and turpentine. This is considered the original frankincense of biblical times and is a very complex smell but in most cases, not the overall most refined smell.Frankincense Frereana - this is the most 'known' frankincense smell. The smell is very well rounded, a near perfect blend of woody/turpentine, with a far distant citrus note. Most resin's are made from this so you are probably most used to this. It is generally the most used because the smell isn't overly complex and is a wise middle ground choice for virtually any use.Frankincense Carterrii - this isn't very common. The smell of this is arguably the best of the bunch. The smell starts off with a high note of citrus, the mid notes are turpentine/woodsy, and it trails off with a spicy scent. It's complex, virtually as complex as sacra however with a different note combination.Frankincense Serrata - this one isn't in widespread use from what I can find. The smell of this one is actually the least complex and most harsh. Most of the notes are strong turpentines, the citrus note is second to turpentine, and the woody scent is so far trailing that many people may miss it.If I had to pick my favorite it would be Carterrii, the entry point of nice citris and near perfect middle blend of turpentine/woody is pretty attractive I must admit.. Frereana is too common, I smell it all of the time and it's just not overly complex enough for me to enjoy. My least favorite is Serrata as it's unmistakably harsh and at times almost unpleasant.However one of the best I have ever smelled is actually a blend of serrata, carterii, frereana. This is incredibly complex and uplifting smelling, and the overpowering nature of serrata is tempered by the other scents. The famed 'Frankincense Trinity" is actually serrata, carterii, frereana. It's much cheaper to make your own... But honestly, if I was mixing them I would remove Serrate and do sacra, carterii, frereana for the overall best and most potent mix result.As for benefits between the versions, they are reported to be; (although I cannot vouch for the source entirely)Boswellia serrata: Supports a healthy response to oxidative stressBoswellia frereana: Supports a healthy response to inflammationBoswellia carterii: Supports a healthy immune systemOverall, it's generally considered best to blend frankincense for a broad spectrum of support, benefits, and cleansing/purification. Each one has a different scent, different notes, and different energy signature.