I keep hearing about how good Twsited is, but I never had the chance to play it, living in Europe and all. ;( I suppose I could import it? Legal issues aside, of course. I'll see if I can.
I only own the original and DIY. I played touched and smooth moves however, and I especially liked the latter. I'm thinking of buying it personally, because I had a lot of fun with it when my cousin had it and I'm in a Wii mood haha. Warioware is really a one of a kind series. One of its biggest strengths imo is the soundtrack. The original especially is phenomenal! Since I'm assuming you like it as well, you should check out Wario land 4's OST. It's from the same composer, and Mega Microgames actually borrowed a lot of from that game. Does this in particular sound familiar to you? Artstyle is also a big one.
I'll be frank, if it weren't for Wario Land 4 (which is my favorite game in general), I probably wouldn't have cared much about the series. I made a whole post about that game and why I like it. As much as I like all other Wario Land games, they don't even come close to 4. Shake It is the closest in its formula, but I fear it's arguably the weakest of the games. The production value, as you mentioned, is great, with endearing aesthetics, music and personality. The problem is with the gameplay in general: Wario feels more stiff and sluggish (It's maybe that I'm used Wario Land 4, which is pretty fast-paced and has a sprint button), and the level design and difficulty only really show their fruits when you actually go for a challenge, otherwise it's a repetitive and easy experience. It's still a solid entry regardless, and I personally rank it higher than Wario land 1 and equal to 2 so far. I'd give one of the games a spin though, if you have the time. They're all completely different and experimental in a way. Wario Land 1 is the most linear, and it's a more traditional platformer akin to Super Mario Bros but "Wario"-tized and has elements of a beat em ups. Wario Land 2 is a huge huge game with so many different paths to take and it emphasizes puzzles and exploration, although it is the only game without a world map. (until you beat the game once that is.) Wario Land 3 is smaller in comparison, but is a Metroidvania with a day/night system that can change a level in its world map entirely. Wario Land 4 is perhaps the shortest of them all if you don't consider the difficulty system which is imo a huge part of the game, and it's an off beat platformer but very fast-paced and has more action than the more puzzle oriented predecessors. (It has the best level design though, and as a matter of fact the game that makes most use of the enemies to your advantage.) Wario Land Shake It! has the same exact formula of 4 but a different core in that it's a more relaxed and a vast game, without the action and pacing of 4. (Now that I think about it, it feels a lot like Wario Land 2, but with Wario Land 4's formula.) It's also the first Wario Land since 1 to not have the shoulder bash -> slide cancel. :''''(
Rhythm Tengoku is my first ever import haha. I might import the Ouendan games and Densetsu no Starfy 3 though, those games are actually kinda cheap today.