Katakana looks cool and futuristic
Katakana characters are basically used for imported words (nouns) from foreign countries, or products invented in modern times. For example, Banana, Gorilla, Computer, Smart Phone are all written in Katakana. This basic rule has now changed and people today, especially people engaged in the advertising business, frequently use Katakana as alternatives to Kanji or Hiragana, so that they can add some kind of "fresh look" in their writing style. It seems effective use of Katakata is crucial to create catchy names, for products or company's.
Hiragana is Kawaii.
Although Katakana is getting popular, it doesn't mean Hiragana characters have lost their charm from the cute or Kawaii looking. and young people (especially girls) love to use them very much.
For example, I use Hiragana to write “Thank you” to friends as it looks warm and friendly. Thank you in Hiragana is; ありがとう
For business letters, I use the Kanji and Hiragana in combination as it looks formal. Thank you in Hiragana is; 有難うございます
Thank you in Katakana アリガトウ is rarely used as it looks rather too cool.