For an explorer-type ship I'd likely go with (in this order) Endeavour, Discovery, Intrepid, Endurance, or Inception.
For a warship... Invincible, Dreadnought, Defiance, Victory, Hood, or Warrior.
I personally don't like the USS in Star Trek, I've often wondered if Gene Roddenberry actually knew what it stands for when he first wrote Star Trek, it should be something like FSS (Federation Star Ship), UFSS (United Federation Star Ship), or my personal favourite FSV (Federation Star Vessel).
It's not a slur against the Americans, it just doesn't make sense to me and hurts the immersion in the game, imagine if he had chose HMS Enterprise and every time you heard it you'd blink like I do hearing USS.