I've read its better than the LG and that is my only real alternative.
reviews are usually positive, but real life performance is often different.
the lg g4 looks great with the leather back, but that leather cover easily wears out at the corners/edges. it's an issue lg have already acknowledged.
i usually look to devices with an outstanding price-performance ratio, so i wouldn't pick either of those, but if somebody put a gun to my head, i'd pick the "normal" s6. the s6 edge looks fab on photos and also in flesh, but not good to hold in hand. it's too slippery, i bet anyone would drop it within the 1st week of usage. the lg looks and feels meh, except with the leather back which is not too durable. so it's the s6 for me.