It depends on the party composition and your playstyle. Chanters are the best trash mob cleaner in the game. Dragon Thrashed + Combusting Wounds will kill everything, especially if you can reliably debuf fortitude and/or reflex. Chanters also have extremely low micro requirements.
If you have a priest, most of what a paladin does can be replaced. The best support a Paladin provides is via single target accuracy buffs. So if you don't okay with a priest, a paladin will make the really difficult fights a lot smoother. Additionally, if you plan on playing with story companions, Pallegina has some awesome personal offensive skills as well.
I personally prefer chanters because I like having at least one character that I can just completely ignore while they go do their thing. I also tend to play with slower but sturdier characters, which means the chanters can even get their invocations off in most early-mid game fights. Also, I like Kana while Pallegina annoys me so that's another reason to go for a chanter for me.
By the end game, even in PotD, the difficulty falls off a cliff so just pick whichever class sounds cooler to you.
