Most of the common names are taken, but there are pleanty of names out there. Many times the name doesnt need to be exact to get the point accross. Im sure there are many easy to say names, just not that sweet squeaken one you want (ACE is taken ta know...along with Yeager, and a few other names people want).
I would not choose a name with a number after it like ACE31, if its a currently active handle. Makes you less likely to be recognized as theres prob an ACE51 and an ACE47 too. Also Gunman** would be a poor choice....trust me!
No matter what you choose, pick something easy to recognize ( ILLIJILLI is imposible to blurt out in combat, and try not to pick something that would cause common mispronounciation (Sutpld comes to mind...he got called stupid about 75% of the time). Choose somthing with either one clean sylable ( POT, KOT, HOT etc) or two distinc sylables (REDHOT, ICEDUDE, PERKMAN ect) for the ease of use of your fellow players. In the heat of combat, the shorter the name the better....OH, and do not choose a name that is common in radio chatter, take it from me (2late4u), it was a nightmare because peope where always saying "I was too late, ooops too late, check six bee...too late sorry"...never knew when someone was addressing me directly and not making a statement about being "too late"