That's a really difficult question. The big problem is we don't know which ones he has tried nor which ones are actually available in your area. If he loves ales, foreign and microbrewery beers he probably goes out of his way to try everything that shows up in the local beer bars and specialty stores.

On the other hand, you can't go wrong by buying him some good beer unless you buy something exotic sounding that is from a non-beer drinking country and/or has been on the shelf too long. So don't try buying something from, say Greece or Turkey or Mexico or Vietnam etc. You want to stick to Belgium, Germany, Britain, or even the USA. And don't buy from a shop that doesn't seem to be doing a big business in imports and craft beers.

Since it is a gift, I'd say presentation matters. In other words, one of the beers that gets sold in fancy bottles, perhaps with an amusing name. That doesn't mean poor beer, quite a lot of the best brewers put their beer in fancy bottles as the price of their beer is high anyway, and many use colorful names to help be remembered. One type of beer along these line would be a good Belgian Abbey Ale. If your husband has ever mentioned liking Chimay, he may appreciate one of the others that are less common. Delirium Tremens (it has a pink elephant on the label) is an excellent one I have tried recently. Another fancy Belgian would be any brand, perhaps Lindemans, of Gueze. That's a beer brewed with wild yeast that is quite uncommon here. Lambic beers are similar but sweeter. From Britain there are a number of good British ales that have humorous names and labels. Monty Python's Holy Grail Ale comes to mind, there is also Hobgoblin, Skull splitter, and others that you will find near each other on the shelf.

Taking another tack, since it is your anniversary perhaps you would consider an American beer: Sierra Nevada Anniversary Ale. They brew a batch with the year date every year and it is always excellent (as are the other Sierra Nevada beers).

I hope you live somewhere that has specialty wine and beer shops so that you can actually find these brews. If you have to go to a grocery store, the Whole Foods Market carries a lot of great beers. But don't buy organic beers unless you watched the truck pull in with them, they don't last. Whole foods carries both regular and organic brews.