Little late on this but its helpful so... lines are normally preferred because they are usually all made by the same person... if you find a good line you can usually trust the ships to be well made, also many people have specific lines they use to mold to their commander bonuses, like why use a ship line that has max abs and acc if you have bonuses to add to that.. its just a waste.. also its easier when upgrading.. you just go by the next ship in the line instead of calculating what price ship you need to buy next, and all lines are different.. some go from 5 mil to 30 bil, and some start higher and such.. a few lines to try
Midnight - old but still decent designs.. be careful because he made many ships and not all superships
Prophets line - good line with many prices
C07 line - Mine
and dont start till larger ships around 400 billion
Xander - Smaller ships.. good to start the game with but stops around 30 billion credit ships
Along with many others.. many people have their lines private so other commanders cannot buy their ships