I'd suggest going straight Ranger. That gives you a +3 BAB, base +2 in all saves, +2 base defence, 4 extra hit points (2 per level) and 6+Int skill points per level.
Class skills are:
Acrobatics (Dex), Athletics (Str), Computer Use (Int), Concentration (Con), Diplomacy (Cha), Drive (Dex), Intimidate (Cha), Intrigue (Cha), Investigate (Int), Knowledge (history, law, philosophy, specific culture, specific local or tactics) (Int), Linguistics (Int), Medical (Int), Notice (Wis), Pilot (Dex), Sense Motive (Wis), Stealth (Dex) and Subterfuge (Dex).
Class features would be:
2nd level: Places Unseen. A +2 bonus to Stealth and Subterfuge checks.
3rd level: Between the Darkness and the Light. Choose a bonus feat from Alertness, Blind-Fight, Brawler, Combat Expertise, Contact, Data Access, Dodge, Die Hard, Endurance, Great Fortitude, Harms Way, Improved Critical (dennbok), Improved Feint, Improved Initiative, Improved Trip, Improved Two-Weapon Fighting, Iron Will, Lightning Reflexes, Nerves of Steel, Point Blank Shot, Resist Scan, Run, Skill Focus (any), Spacecraft Proficiency, Surface Vehicle Proficiency, Toughness, Two-Weapon Fighting, Weapon Focus (dennbok), Weapon Specialisation (dennbok).
You need to qualify for the feat normally, note that some prerequisites are different in the B5 game.
Also +2 Influence in Rangers, and +1 in any other two influences per level.
And, of course, a 3rd level feat. If you have 4 ranks in Athletics, Natural Athlete is a cool one to get.