Hi, I have tried all 3 of them, so I'll tell you what works best for me.
As far as lasting, they are all super concentrated and last a long time.
Biosilk worked great at the biggining, but eventually started to really dry out my hair. It is loaded with alcohol so that is no surprice. It is basically oil and alcohol. That is why you hace to shake the bottle every time before using it. It has no heat protection, so is basically just a smoothing agent. It is also super expensive, compared to the other two.
PM skinny serum, works great, but is a little too heavy for me. I tends to make my hair oily faster then heat glide. I also don't believe it has a heat protectant. However it worked really good, and left my hair super soft and shiny. If I wasn't able to find heat glide I would use this one instead.
Heat glide works great for me. It leaves my hair, soft, super shiny and super straight. It is not oily as long as you use just a little, since it goes a long way. It is great for heat protection. I blow dry and flat iron my hair and it always looks great and my stylist always complements me on my hair, so it must be working.
I would go with heat glide or PM skinny. It is just a matter of figuring out which one works better for you. They both last the same and cost the same. A bottle lasts me well over a year. I would stay away from the biosilk. It is just not worth it.
Good luck and great hair