KLIA is the international airport which is 45 mins or an hour away from downtown KL so if you dread the journey, distance, traffic and inconvenience then Subang airport at the heart of Petaling Jaya in Selangor is the most convenient place to fly into or fly out from.
Subang Airport is the old international airport before KLIA was built-in so it's a bit small but due to the proximity to KL, it's most convenient to travel from. I stay at Bandar Utama so it took me about 10-12 mins to reach.
I took a flight TY2143 from Subang to Johor Bahru and the flight was quite smooth and was served with light refreshments. Firefly serves several domestic cities and regional places like Singapore, Bandar Aceh (Indonesia) and Phuket (Thailand). I'll definitely use firefly again in the future for the convenience of landing into Subang airport.