I definitely prefer advents too. If you're rank 60+ it takes over 4 hours to fill up your AP, while BP still get maxed in 1:40. That means you either play raids around the clock or spend a good amount of seeds into it (not to mention them being a lot more annoying with lags, other people making your fights harder, PP being basically purely dependant on damage, etc). Advent you can just hop on 2 times during the day, do 2 ults and in then evening spend a couple half elexirs on it. Raids i always feel like i'm missing out when i'm not online for a few hours.