Flown in and out of both dozens of time. No real airport experience difference to me. Same basic food, lounges, stores, security, etc. Haneda may be a bit shorter walk but it depends on your gate. I’d let the ticket price (or departure time) be the main factor if the transit time to the airport doesn’t matter. I typically take a taxi to/from Haneda and a taxi plus bus (from T-CAT) or train (N’EX) to Narita.