At less than ¥2000, the limousine bus is a pretty good deal for getting to the airport, especially if you’re not staying in downtown Osaka. I’ve taken the Keihan Airport Limousine Bus several times and it’s been punctual each time. I’ve only taken it from Moriguchi Station. I usually check the schedule online and then arrive about 40 minutes earlier. There’s a ticket machine by the office and it has worked flawlessly each time. After purchasing the ticket, I drop my bags off at the idling bus and walk around the station a bit. The bus leaves promptly and usually arrives at Kansai on time, if not slightly early. I haven’t tried to take the bus during rush hour so I can’t comment on punctuality during all hours. Moreover, keep in mind that it’s first come first serve. While I’ve never been on a full bus, I imagine there’s still a risk.