EDIT: Just so you don't have to read all the below: Kelvin Class and some older ships.
For me, I have to think of the ships in the context of a story.
So, here is the story.
The federation helped to establish a number of colonies on planets in a vast backwater area of Federation Space (The " Back Frontier"). They wanted to secure and eventually develop the area it as an expansion of the Federation and a bufferzone. Unfortunately, tensions and conflict along other borders led to the massive area generally being ignored. Colonies fell in to disarray and despair. Marauders from multiple races (including some of the colonies) generally wiped out the space fairing trade capabilities. In the haste to establish the area, not all of the systems were properly explored and there are some "surprises". Lawlessness is rampant.
To add to the problem, the Federation for many years has used the area to dump refugees.
Starfleet doesn't seem to care - the area is not of immediate concern, but the Federation finally sees a problem - or at least some folks do. They direct Starfleet to secure the region.
So, they dispatch 4 ships. Two old style Ptolemy ships set up as freighters. One very outdated but well maintained and modified Saladin class battle scout (with its own story), and a new Kelvin class ship called the USS Reluctant which Starfleet can spare because deep space missions are at a minimum. Problem is, the real reason they can spare it was that it was commissioned hastily to make room for more relevant ships in dock and they were already about to decommission it - so it may have a few "issues".
The Crews? Rag Tags or ready to send to pasture. The Reluctant's captain? A man who by all rights should be on the lines - but liked to make reality clear to Starfleet a little too often - and is near broken.
The mission? Re-establish order, diplomacy and trade, with an escort on the freighters. Silence the complaints and embarrassment for Starfleet (but he and the crews will do more than that - He will take possession of the situation and in helping everyone else, he will help himself).
Finally, the area is not totally devoid of support. There is a K2 class space station that was towed out long ago. It's basically 2 K class stations glued together. It was once owned by Klingons (sold to them) then they sold it do a Hartford Mudd - an entrepreneur who made a (failed) resort of it, left it to his nephew, James Kahn, who is not an entrepreneur and thought it would be a sure bet moving to the "Back 40" where it would be a meeting place for all of the leaders of the colonies to discuss issues. Luckily for him, part of the mission to refurbish the station so that when the Federation visits it seems all is OK. They send a designer with the captain. Unlucky for him, there are no supplies sent, and he is tasked by the Captain of the Reluctant to make it seem like a high class place worthy - not of the Feds - because they will never visit (but at some point they do) - but of hosting high level meetings between colony leaders in a way that makes it seem like the authority/support of the Federation exists.
And lastly, there is a TOS dreadnought docked at the station. It was a relic when it got towed out. In theory it functions, but in reality it was used as extra space for housing refugees before transporting them to colonies. Now it sits docked to the station and hasn't even been boarded in years.
Lol....sorry - I know that is not what was expected. But that is my lame vision of the next series I would like to see - and the ships...With the Reluctant (Kelvin class) being the main one.
EDIT - yes, now that I have more time, I will admit I accidentally posted to the wrong thread.