... Of course at this time in development nothing is yet 100% finished, so things might change in the future.
Para_Bellum hit it right on the mark, things have, are and will change from patch to patch. Tweaks to the flight models, durability and balancing between ships is typical and even some size/purpose and looks have changed on a few ships which were developed first. Just keep that in mind... game is 'Alpha' and there's a lot of balancing that still needs to be worked on via testing/us playing.
My favorite ship to fly so far is the M50, but my plan all along is to take an Aurora or 315P (depending on what I'm doing) to start playing the game. Again... no rush on choosing "the" ship, there's still a ways to go before they remove the ability to buy different ships (with real money) i the game. Most of the ships will be available during special offerings throughout the year. In November, most ships will be available to everyone to purchase during the Anniversary Sale (Game's anniversary... and they're not reduced in price, they're just available for purchase).
Enjoy the free fly days... take advantage of people in the universe offering to let you fly their ships... have fun.