I usually make a stop at Pho Kim Long during my Vegas trips. Friendly and quick service 24/7.
Everything I've tried has been great, but my fave is the fried rotisserie chicken. Skin is nice and crispy and the meat is juicy and flavorful. It is served with red rice, which is another plus.
Place gets super packed on Sunday when people are nursing hangovers and getting ready to head home, so come early.
Price is good for Vegas. Make sure you check your bill because gratuity is added for parties of 5 or more.