The PSP-3000 offers a noticeably superior visual experience compared to the PSP-2000, despite identical internal hardware (CPU, GPU, RAM).
Early PSP-3000 models introduced a subtle interlacing artifact (horizontal lines on solid colors) due to the new screen driving method. Sony revised the screen in later production runs (often called "3000 v2" or "4g" models) which largely fixed this. Check the date code (later 2009+) if buying used.
Verdict: For the best visual fidelity on original PSP hardware, the PSP-3000 (later revision) is the clear choice. The PSP-2000 remains excellent for homebrew/CFW flexibility (fully hackable motherboard TA-085v1/v2 vs 3000's limited exploit path).