So, I've been playing each race to get to get to know the new things I can use and will be facing in battle, but most importantly the starbases.  First off, it seems that the SBs can be modified to what you want them to be but ultimately I see them as this, this is of course if they are all working bug free and how they are intended to work:

The Advent SB is designed to fight fleets and win.  The abilities that it can upgrade to suggest it is meant to be put on the offensive and thats where I believe it will excel at, the front lines or fighting fleets offensively, so, I consider it an offensive SB.

The Vasari SB seems to be designed best to defend.  It is the only SB that moves which is cool and with abilities like an extra shield and an ability to take in debris to repair itself, it seems best to defend against an assult, specially since it can freely move around, thus protecting the whole gravity well and so defending is where it will excel at.  So, I consider it a defensive SB.

The TEC (my favorite, of course) is designed to be supportive.  It has abilities such as making ships, not caps, another to repair the hull and increase antimatter replenish rate in an area around it make it seem to me that its best place is in the frontlines because it can give you ships and repair your fleet, thus act as a support SB.  Now, this means you can use it offensively but I never like using SBs with fleets on the offensive because of the huge risk of losing it but it seems that would be a good place but I like to put them on my border planets to help fight off fleets.  Now, the reason this is my favorite SB is not just because its my favorite race but it is because of its final ability, its ability to selfdestruct and if upgraded twice will insure only the caps will be able to survive this massive explosion.  This is my favorite ability and just because of that ability I could consider this SB as offensive, defensive and support but I think primarily it is a support SB and thats where it will excel.  Of course, I am bias towards this SB which is why I think it can be used anywhere. 

So what are your thoughts on this?  I wrote this stuff cause I was bored but I would love to read what others think.