I suppose I'll have to do

@if($item->attachedto_type=='Company')
    @include('partials.companydetails',['company' => $item->company])
@elseif($item->attachedto_type=='Person')
    @include('partials.persondetails',['person' => $item->person])
@else
    @include('partials.chooseattached')
@endif

better yet

@if($item->attachedto_type)
    @include('partials.'.$item->attachedto_type.'details',['company' => $item->company, 'person' => $item->person])
@else
    @include('partials.chooseattached')
@endif

or

@if($item->attachedto_type)
    @include('partials.'.$item->attachedto_type.'details',['details' => $item->attachedto])
@else
    @include('partials.chooseattached')
@endif