I use split reins. I want long ones because they stay in place crossed over the horse neck, yet still allow me to give rein so horse can lower head, and not be holding rein ends. My reins fit the size horse being used, wiith rein ends hitting horse knee just crossed over horse withers. On my little horse those are 7ft, while the big horse with long neck takes 8ft reins.
I usually ride 2-handed, which keeps me equally balanced thru shoulders and body on long rides. 2-handed prevents many bad riding position habits from developing, like leading with one shoulder or shoulder and hip as you ride along with twisted body. That is hard on you and horse with uneven weight distribution in the saddle.
If you should drop a rein, STOP the horse. Swing down, get the dropped rein, put it back up and remount. This is the SAFE way to fix things. Seen too many “accidents” happen when rider is lazy, leans forward to grab dropped rein. Horse steps on rein, rears in surprise, maybe gets poked by boot in the flanks to jump forward, riders slide, slip or are thrown off by surprised horse.
The ONE TIME I did not use split reins was with my small son, figuring he would drop them. We crossed the river, came to a sandy spot where his horse laid down to roll! He stepped off pulling the rein, so she JUMPED UP ripping the rein out of his hand. She proceeded to run all over, down the trail a long way. I thought we were going to lose her in the National Forest! She didn’t seem to care about leaving the other horse, son couldn’t catch her. No split rein to fall and step on to halt her antics. I really kicked myself for using the one rein on her. We did eventually snag her, got things back on track in the fun dept. It was a weekend of learning experiences for me and son. Sure glad to NOT tell husband we lost his new horse! Never been trail riding with one-piece reins since.
I don’t care for weighted reins. Weight adds swing as horse walks and trots on a loose rein. I think movement is irritating on the mouth, he learns to ignore the swing so horse “does not hear you” when reins get lifted, shifted, in signaling him.
I like reins that fit my fingers, not an inch wide or so narrow thay can cut into your hands when pulled. I usually use leather reins, but have some narrow braided cord reins that are nice in wet weather for good grip. They have poppers on the end to keep them hanging down well while riding , plus can be washed in the machine! Small son used them on trail rides after that first one, fit his small hands well. He never did drop a rein, though we had practiced the safe way of stopping, getting off to retrieved a dropped rein .
I have the tie-on reins, but use Para cord instead of a leather string. Stronger, very visible if it starts to work out of my knot system. String is longer to allow more knotting. The reins with a metal loop and leather strip lock on rein outside are easy to put on or off, neat appearance, don’t come untied.