I fly regularly with Binter between Las Palmas and Tenerife. I find the airline generally punctual (except for extreme weather conditions - usually at Tenerife North) and the staff very attentive. Fares can be pricey but if you choose your flight times during the day you can get some good deals. Occasionally I have flown with Islas Airways but have found them unreliable and subject to flight cancellations which has been most inconvenient. Their ground staff also tend to be uncommunicative.