Well, you obviously never tried an Akkan start properly, that ship is the second best TEC ship after the Marza, and the best starter with good support abilities.
Akkan is by far the second best cap ship for TEC. A lvl 6 Akkan with Armistice is incredibly useful, as long as you micromanage. Targeting Uplink is amazing on the higher levels, especially if you're someone who likes to spam lrfs. I have always felt Ion Bolt is a bit over-exaggerated seeing as its duration is quite short, but if you stay incredibly watchful over your - and your enemy's - fleet, then it can be of decent use.
For the Advent part, how can you rate the Progenitor and the Halcyon to be the same level as Rapture, Discord and the Radiance? rapture is a useless ship, Discord runs out of antimatter too fast and the radiance does not have sufficient firepower to be a good starter, only useful when enemy titans are deployed.
Okay, where do I begin here...
The so-called "useless" Rapture is an excellent Advent cap ship, you just obviously haven't played Advent enough to value it. When I play Advent, I always start with a Progenitor, but depending on how the game is going I will debate between a Halcyon or Rapture as my second cap ship (which is usually always after my titan).
What deserves the title of "useless" is the Discord. Its abilities use too much antimatter, their duration is horribly short, and the ship itself is relatively easy to destroy seeing as it really provides little to no fleet support.