I actually like HE101 and Mane Depot's sealants. Reason being, that the viscosity of the sealant is nice and thick. It's easy to work with. It dries clear, and it works. HE101 will let you order tinted sealant, but I suggest you use a few drops of hair dye to change the color of your sealant to match your weft.
The thing with sealants is that the safe ones (non-toxic, for use on fabrics, washable, etc.) are often resin-based, silicone based, or latex based. The problem with that is, as we wear our hair, the oils from our hair breaks down the seal over time. I've had to re-seal wefts more than once.
When it comes to using sealants that arent marketed for sealing (nail polish, crazy glue, culk, hot glue gun, etc.) you still can run into the oil break down, but also, you can damage your wefts by over applying.