I’m glad you asked, I want to see what others think!
My first snorkle was a great big honking dry snorkle of unknown manufacter with a ball swivel that held the mouthpiece in position wherever you put it, a large bore rigid tube, and a purge valve. It was totally dry and very mouth comfortable, so well sealed it sucked my tongue in when I went freediving, not knowing I should spit it out. It was uncomfortable on the mask strap and terribly top heavy, but if I am ever stranded in high seas I will probably regret that I stopped carrying it.
Now I also have an assortment of unsatisfactory snorkles, all of which I dislike. The scubapro accordion flexitube type requires too much jaw-aching teeth gripping to hold. All have crappy mouthpieces. I did have a simple j snorkle from xs scuba that was ok for freediving in calm water, but a jellyfish stung my hand in my local low viz and I dropped it. I would get that again.
I rarely carry one scubadiving, but I want to find a way besides mask strap to bring a good one along in case. Maybe a DIY thigh holster? I tried a roll up pocket snorkle but the mouthpiece pops off in the pool, and it is terrible to breathe from because of the narrow, crushed bore. Basically a POS. Assuming I might need it OOA in high seas why have that.
I’ve also discovered that the simple snorkles freedivers love are NOT good in big waves where water “poops” down the tube, causing choking and dangerous water aspiration.
I want to try no BC diving and will need a good snorkle for that so I’m eager to hear what others recommend.
Also what is the most comfortable quick release retainer system?
