We chose mainly due to ports of call. Usually we go Celebrity.
Comparing Celebrity: younger average age (I read that Hal was trying to get their average age lower), more entertainment (Celebrity has a great Martini bar that is very active before and after dinner and has entertainment on pool deck, in lobby). In nightclub, HAL was very quiet--it only came live when our younger average age group attended but we had to educate the DJ. Live band in nightclub only 2 nights out of 18. Food and service was excellent. Spa was great. Some ports of call was a bit disappointing but educational. Final Disembarkation in San Diego was very disorganized on board with long lineups stretching down the ship hallways. Fitness club was great--no waiting for most equipment (likely the benefit of older average age). Public rooms on Celebrity always had attendants keeping everything clean vs Hal. Celebrity always had greeters with hand sanitizers at eating hall entry ways encouraging people to sanitize hands. However on HAL, food was more secures as everything was served (i.e. not selfserved)
a bit out of date furniture and colors. bed was fine. AC was fine.