I will second the idea that it's not so much the Commander that matters, but how you decide to build them.
Even so, there are several Commander options from recent sets that offer more niche gameplay and deckbuilding challenges:
Eutropia the Twice-Favored - Eutropia needs both enchantments and creatures to work effectively. You could easily build her as voltron, or as an enchantress deck - but you can also look into a Bestow deck or other kind of value driven enchantment flickering deck.
Haktos the Unscarred - typically a voltron style, but not knowing what number will get chosen makes equipment and auras hard to build. Instead, some non-targeted buffs and anthems is what you want. Cards like Pyrohemia can be interesting, as if you don't roll a 4, he'll be immune and you can keep damaging the board. Possibly flicker effects (Restoration Angel) to flicker him if you land on the wrong number.
Kunoros, Hound of Athreos - GY police. Easily a voltron style, but you can probably also work some ways to use the GY lockdown to your advantage.
Questing Beast - fog tribal. With Questing Beast making your team immune to fogs, you can attack with impunity into enemy forces and then fog to make combat one sided.
Torbran, Thane of Red Fell - I saw someone mention mono-red superfriends with this guy at the helm, but there's a lot more fun to be had. Cards like Pyrohemia become far more deadly. Just remember to give him protection from red or indestructible first.
Even so, there are several Commander options from recent sets that offer more niche gameplay and deckbuilding challenges:
Retired EDH - Tibor and Lumia | [PR]Nemata |Ramirez dePietro | [C]Edric | Riku | Jenara | Lazav | Heliod | Daxos | Roon | Kozilek