Alectai
Speaks Words of Wisdom... On occasion
We need high tech scanners and science stuff on a survey ship though, the sphere feels like it provides the most volume. I mean look at the Antares-type (which is apparently used for literally everything in the TOS era including surveying), not a sphere but it certainly has a bunch of internal space a flat saucer cant provide.
ORB and Half-Saucer explicitly have the same internal volume at the end of the day. The only difference is that ORB is cheaper because it's a very simple design and gets the same volume at a 20% reduction in total mass. But straightjackets everything that comes afterwards while also fundamentally limiting its ability to maneuver and defend itself by presenting a hilariously easy target profile in all directions and straight up being incapable of firing behind wherever its phasers are mounted.