Current aptitudes are ill-suited for specialization for their sake.
Currently, Technology is probably the most obligatory for everyone. If you do not have Electronic Warfare 1 and you do not use pure carrier fleet, you get burned frequently late in the game when a significant number of fleets have Electronic Warfare and you do not, and you lose 10% or more to your shot range right off the bat. Also, Loadout Design 3 is great for everyone.
Similarly, if you even want to dabble in fighters, Fighter Doctrine 3 is very useful. Leadership has very useful skills.
Combat 1 is great for Combat Endurance 1, but beyond that varies widely with what you want to do and if plan to be married to a particular ship late in the game or not.
Industry is divided into two sections - cheaper combat (first three) or crutch free one-off money skills (last two).
Even if you want to specialize, you need to cherry pick from various trees. For example, carrier fleet, your probably want Combat 3 for Helmsmanship (zero-flux speed while fighters Engage lets carriers flee much more easily), Leadership 3 for various skills, and Technology 3 for Electronic Warfare 1 (if you have non-carrier escorts) and Loadout Design if you want to stuff your carriers with high-end fighters and still have enough OP left to afford hullmods you need and some vents.