I am looking to know which kind of caulking would be best suited to seal the edge where a tile backsplash and arborite counter meet. Specifically the area behind the sink faucet. There are so many available it is a little confusing. Thanks for the help!

What you need is silicone. Specifically kitchen and bath silicone. Not all are created equal. GEII is pretty good, but my personal favorite is Dow Corning 786 silicone sealant rated for food plant use. The best color is translucent white, but clear will work too if there is a nice corner bead of grout under it.

Work approx. 10' at a time. Apply a small bead and immediately smooth out with a finger dipped in soapy water. have tissue ready to wipe finger clean. After about two minutes don't touch it again. Masking is a good idea, but not necessary with the right touch.