The only time I think that a Llanowar style elf is better than Hierarch is when you have a lot of elf synergy
Absolute Virtue Aettir and Priwen Ancient Adamantoise Buster Sword Clive, Ifrit's Dominant Cloud, Midgar Mercenary Cloud, Planet's Champion Dark Confidant Emet-Selch, Unsundered Esper Terra Gogo, Master of Mimicry Hades, Sorcerer of Eld Ifrit, Warden of Inferno Kefka, Court Mage Kefka, Ruler of Ruin Lightning, Army of One Nibelheim Aflame Sephiroth, Fabled SOLDIER Sephiroth, One-Winged Angel Sephiroth, Planet's Heir Summon: Bahamut Summon: Knights of Round Terra, Magical Adept Traveling Chocobo Vivi Ornitier Y'shtola Rhul Yuna, Hope of Spira
Conversely, you can play a slightly lower land count if you have access to non-lands with cycling
This sorcery should not be underestimated, as casting a one-sided board wipe can often make a game-changing difference to a game of Commander
In general Tron decks are not overly concerned about card advantage or tempo