I am reviving an old thread here but I also needed a reliable way to target a repeater row.
@benjamin your recommended logic worked. The only downside is that if the repeater rows are reordered, it will change what is presented on the frontend.
I found a blog with a simple way to add a unique ID field to ACF with a little PHP. Working great so far. 
https://second-cup-of-coffee.com/creating-unique-ids-for-acf-repeaters/
Once enabled you can target repeater or flexible content items like this:
<If check="{Field banner_id}" is value="6575401d978b0"> ...content...</If>