The general rule is that the French and Swiss ones are the best and are REAL absinthe, made in the style that was popular during the Belle Epoche. 99% of Czech absinth (note the lack of an "e" at the end) is almost an entirely different drink, made a different way, usually lacking the strong anise and fennel flavors that characterize real absinthe, and (in my opinion at least) is piss-water that only sells because of their extremely gimmicky marketting. Some absinthes are made in Germany, Austria, and Spain, but they really vary between brands in quality.
Absinthe won't make you trip or see crazy stuff...it just gets you really drunk because most of it's bottle at around 120 proof :laugh: Only thing I've noticed about it that's different from other alcohols is that it creeps up on and makes for a very lucid, clear-headed intoxication if you drink too much...you won't even know you're drunk until you stand up and your knees start wobbling.
Most modern studies have determined that it's probably the fennel and other botanicals that might give you that strange intoxication, not the wormwood or thujone it contains. The reasons it was made illegal (and note that it's banned under FDA rules as a poisonous substance sold as a beverage, NOT the drug scheduling that stuff like cocaine and heroin are contraband under) in the first place are pretty much bogus...you'll die of alcohol poisoning LONG before the thujone will have any negative effect on you...and plus, sage and tarragon have high levels of thujone as well, and nobody's died from eating Italian food. :laugh:
If you like strong, anise/liquorice flavored beverages like Jagermeister, raki, ouzo, or pastis (which is basically absinthe without the wormwood to make it legal), then absinthe is worth a shot. Just don't light your sugar cube on fire, because that's another invention of the Czech absinth marketting machine.
Some good brands to look for are: Clandestine, the Jade line of absinthes (made by Ted Breaux, a really cool guy from New Orleans who moved to France to make authentic, old French-style absinthe), Montmarte, Fougerolles, and (believe it or not) Marilyn Manson's Mansinthe.
Stay the hell away from Hill's and King of Spirits! (BARF)
Here's a good website for info and guides to picking a good bottle:
La Fee Verte