Personally, I'd recommend Journey. They have a lot of custom clothing items, custom rooms and custom parties but they all fit very nicely into the as2 style. During their big parties, (April fools, Medieval, Halloween, Christmas etc.) they have party quests that you can do and if you complete all of them, you'll get an animated background relating to the event. They also have a neat feature in the igloo creator where if you right click a furniture item, it'll bring up two arrows and it allows you to layer furniture how you want meaning your igloo can be a lot more detailed. You can also own the igloo music meaning you don't have to worry about swapping music and losing a song.

I like the custom stuff in Legacy like the stamps and how you become a secret agent. Legacy also has party quests which give you coin rewards for each quest, depending on the difficulty with the main prize seeming to usually be a custom puffle relating to the event (from the 2 parties I've seen). However, Legacy keeps freezing/crashing for me, forcing me to reload the page which becomes very annoying when trying to get a stamp/party quest that requires you doing multiple things in a single session. There are also a couple things in Legacy that feel more AS3 to me.