Leigh McAdam recommends:

Berg Lake

Elfin Lakes, Garibaldi Provincial Park

Elk Lakes – Petain Basin

Eva Lake, Mount Revelstoke National Park

Frosty Mountain, Manning Provincial Park

Garibaldi Lake, Garibaldi Provincial Park

Gwillim Lakes, Valhalla Provincial Park

Howe Sound Crest Trail near Vancouver

Hermit Trail, (Canadian) Glacier National Park

Iceline Trail – Yoho Valley Loop

Juan de Fuca Marine Trail

Kaslo Lake or Kokanee Glacier Cabin, Kokanee Glacier Park

Mount Assiniboine

Nootka Island Trail

North Coast Trail

Rainbow Range Trail, Tweedsmuir Provincial Park

Rockwall Trail

Sunshine Coast Trail

Takkakaw Falls – Laughing Falls – Twin Falls – Whaleback Ridge Loop 

West Coast Trail

Details from Leigh Adams on Hike Bike Travel – 21 Backpacking Trips in BC That Will Blow You Away

Eva Lake in Mount Revelstoke National Park

Having done most of those adventures myself, of that list I’d first recommend:

West Coast Trail