Which is more rewarding: praying behind an imam with a beautiful voice, with whom the worshipper feels devotion, but who does not prolong the rak'ah, or behind an imam with an ordinary voice but who prolongs the rak'ah in Tarawih and Qiyam prayers?

"Devotion (khushu') in prayer is better than prolonging the recitation within it. A prayer performed with devotion and a present heart yields greater reward. Indeed, some jurists have even held that prayer is invalid without devotion. Sheikh Ibn Baz is of the opinion that seeking tranquility and devotion takes precedence over aiming to complete the recitation of the Qur'an during prayer."