My favoite would have to be the mimitchi costume cause its not one use and it can turn your tama into a mimitchi if you would dream of having one lol, or if you don't like ur current character! :0)
i do not like the panda costume very much,as once i had a furawatchi(the one that looks like this: )and i accidently put the panda costume on it and i had to look at an ugly panda thing instead of my cute little tama all day long,and once i got a duplicate of it because my friend had wrapped a panda costume without telling me and are tamas connected and my tama had to wrap the panda costume and give it to it's other friend.i like the love potion best cause it's what saved my tama from turning into an old timer(by making him fall in love with my other tama and having babies with her).you could try changing the time to your tama's bedtime,because it always takes off costumes when it goes to bed.and when it took of the costume,you could set the time to what it really was and your tama would be awake and would not look like a panda.