First of all, there is a fine difference between a tank and a sweeper.
A Pokemon intended to take either physical or special attacks and hit back, but does not have to do so consistently over the entire course of a match.
A Pokemon who uses offensive moves (be it special, physical or both) to do damage and bring down an opponent's team. Many carry boosting moves, like Nasty Plot, Swords Dance, Dragon Dance, Calm Mind, etc....
Electivire is too frail to be a tank and can be outclassed by other electric type, but can still be decent. Compared to the 2, it hasbetter sweeping abilties, because despite it having many checks and counters and all that bad stuff, unprepared teams funnily get themselves dented by an Electivire
However seeing as you probably want a Pokemon that can take hits and dish them out as well, I am pretty sure you are looking for a tank, making this answer all the easier for me seeing as between the 2, only one can be a tank, and that one is Eelektross. With decent bulk and high offensive stats and a great movepool, Eelektross is most definetely the one you need.
For notable sets in this gen, I would just suggest you using an AV Eelektross, depending on the Eelektross you have, I can't easily suggest any moves for it, but I am sure you know that already.
There isn't much more to it really. Eelektross is just a superior choice overall. Superior ability and superior movepool that enables it to counter or check everything it needs to counter / check, even ground types. Something which Electivire can often fail to do without speed control or enough power to KO those bulky nasties.