I've been catching up to lot of post-Goscinny Asterix lately: The Magic Carpet, The Actress and The Falling Sky.
The Magic Carpet is easily the best. I tend to favor stories where Asterix and Obelix go on a quest instead of the only other plot these comics do, which is to insert a stranger in the village and get everyone mad at each other (see: The Soothsayer, The Roman Agent, The Secret Weapon, The Residence of the Gods). Uderzo usually introduces elements that are a little too silly or fantastic by Asterix standards but I liked The Magic Carpet despite, you know, the Magic Carpet (cue as many jokes about the inconveniences of airline travel as possible). It's nice to have Cacophonix join in the adventure for a change, and the three have a really funny dynamic going.
The Actress is a so-so entry that doesn't have any fantasy elements to it but borders on ridiculous due to how contrived the plot is: that Asterix and Obelix suddenly share a birthday (news to me), that their moms visit from Condatum/Rennes with gifts that belonged to Pompey and were pawned earlier at their husbands' shop by some wino, that Cesar wants them back and decides to send over a Roman actress who's a dead ringer for Panacea to seduce Asterix and Obelix into handing over the gifts (how would anybody be aware of Panacea or her relationship to A&O?), etc. It was enjoyable enough, but every aspect of the story felt like a tired retread.
The Falling Sky is by far the worst of the three and probably all of Asterix comics. It's about an intergalactic invasion that pits two alien races that are supposed to represent American superhero comics and Japanese manga in a deluded old-man sense of commentary on the industry. The alien designs are ugly as sin and the sci-fi conceit clashes horribly with the Asterix ethos, who has a relationship to history and humorous anachronisms that is more or less comparable to Monkey Island and the Golden Age of piracy, though definitely lighter and more earnest. The spaceship thing does not work, looks hideous, and it is not worth the commentary.