Group Shield sucks....it has a very small targetting range (4000 m), and then the buff that spawns off that target also has a very small range (4000m), so it's going to be very difficult to actually use that ability on your entire fleet...furthermore, at level 1 you can only have the ability up 1/3 of the time while at level 4 you only have the ability up 3/4 of the time...it also doesn't even affect the titan....it's a pretty awful ability at low levels, and by the time you'd have it at high levels, no one is using frigates for firepower anymore...
Even inspire and impair is pretty awful when you realize is does absolutely nothing to counter bomber spam (it doesn't affect SC) which is the source of firepower late game...
The titans are not even remotely comparable in their abilities...the ankylon is far below the other 5 titans....at low levels, the rebel titans are far better than their competition, and at high levels the Eradica and Vorastra are just absolutely ridiculous...
Before I'd even consider allowing titans to be choices, I'd at least want the "choices" to be comparable...currently, however, they are not....the Vasari titans are both pretty good (though VL obviously banks on getting to level 6), but for Advent and TEC the "choice" would basically just be ragnarov and eradica....
FYI, in general there are 9 unique technologies that each faction has not including the corvette and titan prototypes...there are some exceptions (IIRC AR have only 8 while VL have 11 if you include enslaved labor)...