I'm not sure it is entirely fair to compare the two but... While the technique is superior in the Looney Tunes cartoons I was surprised while rewatching them, how casually racist a lot of them were. I had a lot of complicated explaining to do with my young son.
Rewatching Scooby, I didn't find them overly dated or having unacceptable stereotypes (well at least not as bad - their Canadian stereotypes in one episode were hilarious) as in other Hanna Barbera cartoons or in some Looney Tunes. In fact, despite the cheapness and repetitiveness of them I was surprised to see that most of the early Scooby episodes, for me, held up. The gang always try to uncover the actual reason for the mystery rather than buying into whatever local legend or spooky story they encounter. I think the characters, though vague, aren't too bad. Shaggy & Scooby are comic relief so whatever though they usually have a redeeming moment of bravery so they are not completely useless. Velma is the brains and unwilling to be fooled by whatever crook and figures things out. Daphne is clumsy but she's never treated like a dumb blonde as she would have in other Hanna Barbera cartoons. And eternal cipher Freddie, he's the guy coming up with the elaborate Rube Goldberg traps. A bunch of skeptics unravelling the supposed supernatural phenomena through their wits. At least that's how I see them.
Interestingly, I tried a bunch of Scooby episodes from a variety of eras with my young son and he overwhelmingly preferred the first 3 or so years of Scooby. He absolutely hated the recent reboot.