dtgreene: For purposes of this topic, assume that anything not mentioned is the same between the games, and that battles take place on a separate screen (and are the same between these two games.
Given that, which would be easier to make:
1. A tile based RPG, much like earlier JRPGs (Dragon Quest and Final Fantasy 1-6), or like the overworld in classic Ultima games (but not the dungeons).
2. A first person grid based RPG, much like earlier Wizardry and Might and Magic (and the dungeons of early Utlima).
Panaias: -Tile-based: as others have said, reusable art is always a plus for the developer. But, you also have to handle collisions for every entity that interacts with others and the environment. If you're developing your own framework/engine (been there for a while), you have to deal with this efficiently, especially if there's going to be numerous of them simultaneously.
-1st person grid-based: multiple times more work is required for the art. But, you are also restricting movement to predefined nodes, so no collision handling. For each of your entities, only their surrounding nodes should be checked to react to other entities or the environment.
So it boils down to: code heavy in entity/environment collision/reaction vs code heavy in handling artwork/animation.
(I'm deliberately leaving out details like game logic, audio, shading, timing, input, etc. as these will need much work one way or another)
For the tile-based game, I think I would limit movement to tiles; the only time an entity won't be on a tile will be in the middle of the movement animation, and I might not even have a movement animation, at least not at first.
(The battle system would likely be non-tactical turn based, so there's no notion of positioning, and hence no collision issues there.)
dtgreene: Maybe I should replay Phantasy Star 1? (Note that this will not be the same version I originally played; the GBA version, which is what I played, has a serious RNG flaw that results in attacks always missing in some circumstances.)
Darvond: Eeeeeeeh. There's what, only one version with an automap, right?
You *can* learn how to navigate the dungeons without a map. I've reached the point where I don't need to refer to a map in Bard's Tale 1. (Do note that Kylearan's Tower is particularly nasty done this way; Phantasy Star doesn't even have anything even close to that.)
I recently played through a little game called Magic and Metal Zero, and that has a floor with no auto-map or compass, along with many teleporters and spinners, and I was able to navigate that floor.
(Also, I believe there exist 2 versions with an automap, a remake for the PS2 (JP-only, and changes the mechanics) and a version on the Switch.)