For this first round, I have simply voted for the "best looking Star Wars ships" but for the next round, I will purposely not vote for ships that use a box or a tank as a prison. This is definitively not Star Wars (and no, Han Solo in the carbon freezing solution was more an axception than the rule). In SW, you see or get references of a lot of detention cells, both on large structures (Death Star, palaces like Jabba's, Imperial prisons...) or ships (ISD, Slave I...). I sadly consider the use of tanks for prison as a workaround or a bypass to the rule.
But this is my humble personal opinion and I still wish the very best to each participant.
Kolto tanks are a Star Wars technology, and definitely valid for containment in my book. It's not like that technology didn't even exist at all in that universe. Bounty hunters may have to use excessive force too, so it would only make sense they would need kolto tanks to keep the bounty alive long enough to collect... or administer sedative (bounty hunters also tend to be lone wolves, so they could also use it themselves to heal up). It is a great multi-purpose containment system. Also, it's not like bounty hunters follow rules of convention, or at least the successful ones...
It also depends on how narrow your personal Star Wars universe is, since kolto tanks were definitely used for prisoner containment in Knights of the Old Republic. They also used cylindrical force fields as prisoner detainment cells too.
In the context of this contest, I do agree with tank usage influencing voting... but based on if it was implemented well versus just a "lazy solution"... (I actually have more of an issue with cramped cubby holes for containment).
... with that said, I won't likely be voting for any bounty hunters with light sabers, for obvious reasons