Using ngClass, $parent, $first and the Client View Model with ngRepeat

controller_fragment.js

isIndexSubsetHeaderSelected: function (subset, isFirst) {
    if (!this.routeIndexSet) {
        return false;
    }
    if (!this.routeIndexSubset) {
        return isFirst;
    };
    return (this.routeIndexSubset === subset);
},

partial.html

<div data-ng-if="!clientVM.isSplash" class="col-md-4 col-sm-4 col-xs-10 IndexSubset">
    <h3 data-ng-class="{selected:$parent.clientVM.isIndexSubsetHeaderSelected(i.id, $first)}" data-ng-repeat="i in clientVM.currrentIndexMeta">
        <a
            href="{{i.url}}"
            data-ng-if="i.url">{{i.text}}</a>
        <a
            href="#/index/{{$parent.clientVM.routeIndexSet}}/{{i.id}}"
            data-ng-if="!i.url">{{i.text}}</a>
    </h3>
</div>