I guess it depends on which beers you can get at other times. One of my favorites from the list would be Duvel, which is a gorgeous strong blonde beer. But it's quite widely exported, so if you can get it anytime where you are, you should go for rarer beers. Though if you've never had Duvel, it's well worth a go.
Achel, Chimay, Orval, Rochefort and Westmalle are all trappist beers, and all very good. Rochefort 10 is a big kick-ass beer that I'd happily drink any time. Westmalle do a great tripel, and I like the fruitiness of the yeast that Chimay uses. The Orval uses Brett yeast, so it's very different to the others. It's quite funky, and not to my taste, but I have friends who love it.
Cantillion is very well regarded by Belgian beerophiles, though I think they only do gueuzes and the like, which again is a little too funky for my palate. The same goes for Boon - I've tried their Oude Gueuze and couldn't drink it, but others loved it.
Rodenbach Grand Cru is another highly rated beer. De Dolle do a great 9%stout, though it's quite American in style, so maybe not the one to go for if you want Belgian-ness. Dupont do a fantastic Saison, in normal and organic ("biologique") versions, so try that if you can. All the St Bernardus beers are good, but their 12 in particular is a belter of a beer.
IMHO Hoegaarden and Stella Artois are fairly ordinary, and given how smashed you could get on all the high strength beers, I wouldn't waste good brain cells on them. The only one on the list to really avoid, according to Tim Webb's "Good Beer Guide - Belgium", is Huyghe - he goes on at great length about how their beers suck total ass. He may or may not be right - it's only one man's opinion - but given how many other good beers there are, I figure why take the risk?
All in all, though, that's an amazingly good choice of beers.