PLA and its close blends. PLA, PLA+ and high-speed PLA all carry a difficulty rating of 1 in this site's data, the lowest available, and the selector cannot separate them on ease alone.
What that rating means in practice is a short list of things you do not have to do.
The things PLA does not require
- No enclosure. It contracts 0.2 to 0.5%, low enough that an open frame in a normal room is fine.
- No drying. The only common filament marked as not requiring it.
- No heated bed, strictly. Its bed range starts at 0 — it will stick to clean textured PEI unheated, though 55 to 60 °C makes life easier.
- No high-temperature hotend. 195 to 225 °C is within reach of even a PTFE-lined machine.
- No ventilation requirement, unlike the styrenics.
Every one of those is a thing that goes wrong on other materials, and a beginner learning on PLA is learning printing rather than learning material management.
The next rung up
PETG and TPU 98A both sit at difficulty 2. PETG asks for drying and retraction tuning; TPU 98A is nearly rigid and prints close to normal speeds. Either is a sensible second material.
Matte and silk PLA are also rated 2, which surprises people — they are PLA, but the filler and the additives narrow the process window and increase nozzle wear.
Where "easy" stops
ABS, ASA and HIPS jump to difficulty 4, and the jump is not gradual: they require an enclosure, ventilation and drying all at once. PA6, TPU 85A, TPE, polypropylene and everything above PC sit at 5.
There is no gentle path between rating 2 and rating 4. Skipping straight from PLA to ABS is where most people's second material fails.
The caveat worth stating
Easy to print is not the same as good. PLA sags at 52 to 60 °C, goes chalky under UV, and cracks rather than bending. It is the right first spool and the wrong answer for a great many parts.
Rank ease against your other requirements in the material selector, and see the property set on the PLA page.