Start with the failure mode
Before asking which process produces a nicer surface, ask how the part is allowed to fail. A bracket that snaps under load has failed. A miniature with a soft eyebrow has also failed. Those are different failures, and they point at different machines.
FDM is the default for parts with a job
Fused deposition wins whenever the object has to survive something. It is tougher, it is cheaper per gram, it prints large, and the material range covers everything from flexible TPU to carbon-fibre reinforced nylon.
The cost is resolution. A 0.4 mm nozzle cannot draw a 0.2 mm feature, and layer lines are visible unless you finish the part. Orientation also becomes an engineering decision: an FDM part is meaningfully stronger along its layers than across them.
Resin wins when detail is the point
Masked SLA cures a whole layer at once through a UV screen, so resolution is set by pixel pitch rather than nozzle width. Features well below half a millimetre resolve cleanly and the surface comes off the machine essentially smooth.
The trade-offs are real. Resin parts are more brittle, they need washing and UV curing before they are usable, the build volume is smaller, and the material costs several times more per gram.
The question we actually ask
Would you rather explain a visible layer line, or a part that broke?
If the answer is the layer line, print FDM and finish it. If the answer is the break, and the part is small, print resin.
Where it gets interesting
Plenty of projects use both. On our Riverside Tower model the curtain wall was clear resin at 0.05 mm because the mullion rhythm was the whole point, while the podium was PLA because nobody was going to inspect it at arm's length. Splitting a job across processes is normal, not a compromise.