For someone just looking to play games, this his how I'd rank the reliability / serviceability of the systems....

PC Engine Duo-R/RX - easily the most reliable systems compared to the others at this time

Super CDROM2 - Just now starting to exibit capacitor issues, but by in large still reliable

PC Engine Duo - more readily available than a US system, but capacitors MUST be changed to ensure long term reliability

Turbo Duo - Just like the PC Engine Duo, the capacitors MUST be changed to ensure long life

Pioneer LaserActive + PAC-N1/N10 - Also subject to capacitor issues, though it is not a difficult swap to do. Laseractives themselves are somewhat fragile, and also have laser issues occasionally.

Turbo Grafx CD / PC Engine CDROM2 - Known gear issues are a problem, capacitors are a problem, lasers are a problem, plus system cards are expensive. For a gamer, avoid these if possible!
Just my 2 cents

(ok maybe 8 cents)