It should be possible to use rdfs:label and label:service without conflicts
Example:
SELECT ?item ?itemLabel ?instance_of ?instance_ofLabel WHERE { ?item wdt:P31 wd:Q146. SERVICE wikibase:label { bd:serviceParam wikibase:language "en". } ?item wdt:P31 ?instance_of. ?instance_of rdfs:label ?instance_ofLabel. FILTER((LANG(?instance_ofLabel)) = "en") }