Jungle Beat rocks, but it's less of a sequel and more of a platformer that uses the drums.
Both are fun, but I'd guess the Konga drums have more life in them - Nintendo seems to be pushing Konga pretty hard, whilst Taiko will likely come and go with a whimper.
Either way, there are Japanese sequels that you can import. The problem is Konga doesn't like Freeloader, so you have to mod your GameCube in order to save your game....luckily, modding your GameCube isn't that hard (even for someone who has never used a soldering iron before).
If you're looking to get your money's worth, I'd probably go with Konga. Yea, both games have a "WTF Factor" but Konga's is a little higher, plus it supports up to four people and has a better chance of a sequel/more games using the drums.
No matter which way you go, you win.