The title says it all. I'm saving up for a new champion and am curious as to who will end up being stronger lategame. Thanks in advance.

From a pure damage perspective, Riven will generally do more - she has a lot of burst potential with her ultimate, and a lot of staying power with her shield. But the kit of Irelia is very deceptively strong - if she's sufficiently tanky, she's incredibly difficult to peel off a carry, and since the lategame is usually defined by whose carries stay alive, that makes a lategame Irelia extremely difficult to deal with if she's farmed/fed. So in most situations, Irelia would tend to win out, but it'd be heavily influenced by team comp - if the enemy AD carry is well protected, Riven may be better just for her raw damage if Irelia is unable to reach/kill the enemy AD carry. I feel Jax and Olaf are almost kind of an intermediate step between the two of them - not as good as sticking to an enemy AD carry as Irelia, but higher damage threat. All are strong lategame fighters.

Really depends on team comp and how well mid and planing phase were. Rivens got more burst damage then Irelia but Irelia true damage hurts a lot. Both in my opinion are good at peeling and do good sustained damage. If you want more sustain and true damage go with Irelia if you want mobility and more burst go riven.

Riven is gonna get nerfed badly soon, I'd say Irelia.

I prefer Irelia, but both need early income to remain a threat in late game. If fed, both are fearsome.

The champs play differently. Riven is about doing her combo on a target and hopefully dropping them low enough enough that her ult will finish them off.

Irelia is more of an anti-carry that you use to chase a carry while being rather hard to remove with CC. Well, depends on the CC as well.