Thanks bud - appreciate the advice.I really like both. I think it will depend on what you're in the mood for. Wonder Boy lets you figure things out as you go along, and is unforgiving with check points, so if you die you restart at the main hub. Don'tet this put you off since you can typically be right back at the same spot in 5 mins or less.
Blaster Master is like a lite-Metroidvania, with a tad more story and areas slowly being accessible as you unlock certain abilities as you progress through the game.
Both are comparable in length, Wonder Boy obviously wins in the looks department - really gorgeous in handheld mode.
Will definitely pick up both at some point in time, just want to decide which one I want to play on the plane.