HL1 is easier? And honestly, the technical limitations of HL1 suit the cartoonish look better, I'd think. It wouldn't need any normal/spec/bump mapping or anything, for instance. It's a cartoon.
"Booyah! Look out, LeChuck! Here comes Guybrush Threepwood's glowing sword of hot monkey vengeance!"
-Guybrush Threepwood, Tales of Monkey Island