This is one of the games where I can simply play the characters that I like, while carefully accessing what tools they have available for them. For play style (offline), I resort to passive aggressive play.
If any of you were to see me offline or with a (coincidentally good connection) I will basically play like a Mortal Kombat II CPU but without the blatant disobedience or disregard of the game system mechanic set ups.
So I will most play characters that with a fast walk speed for ground control, pretty much accessing all of the characters strengths as much as possible, as well baiting, reactionary movement, and punish combos).
I play EX Kyo for the sake of familiarization because I play him a lot on CVS, CVS2, KOF98, KOF03, KOF02UM, and KOFXI. I also enjoy his overall character and he makes for a very unique and not so standard protagonist. He reflects my traits on fundamental aspects of KOF fighting games.
For Mai Shiranui... I did play her a lot in 98 (EX Mai specifically) and she had also been a main character for me on CVS2 (with Rock Howard being my priority, as well as playing a quarter of the cast for fundamental and counter-picking measures). Mai is and always will be eye candy for me as I find her pretty funny and hot as hell. My original intent for KOFXIII was to troll people with her. I didn't really think she would be as good as I thought in KOFXIII... until I went to an event in World Game Cup (Cannes, France) encountered another Mai player who nearly OCV'd me. Ever sense then, I got motivated to play Mai in this game too. She pretty much represents my liking of particular strong female characters (and in general). Also she literally does have the tools I need for my play style. An air throw, good keep away, some high priority normals, quick movements, intense corner juggles, an easy 809 damage HD combo for two stock, and a good Neo Max.
Basically, should the game be manageable in the balance department, I will play characters that I like, but I will also access what kind of tools they have so that I won't lose so easily, especially if a tournament is involved. The other characters I am guaranteed to play are Beni, Terry, Joe, Ash, Ryo, Claw Iori, EX Iori, Mature, Vice, Betty, Duo Lon, King, Yuri, K', Kula, Athena, and Leona for the same reasons mentioned above on game play aspects.