The ones that haven't travelled in worthwhile new directions... so pretty much everything there except Mario (Galaxy was excellent, and the main series hasn't become oversaturated), though I'd perhaps be willing to let Zelda and Guitar Hero off the hook, presuming their developers could deliver solid iterations in the future.
Opinions
Final Fantasy - Has been on a downward slide since VI & VII, excepting maybe IX - in any case, the CGI saturation of FFX seemed to guarantee this franchise would never return to relevancy; MMORPG and FFX-2 doubly (in hindsight, actually, Sakaguchi's departure could be viewed as the last straw).
Verdict: end
Halo - I was always critical of Halo: Combat Evolved for its shortcoming - among them a lack of bots, unacceptable in a post-Perfect Dark console shooter with no online play; the repetitiousness of its single-player mode, and design faults like how the largess of its maps resulted in tepid two or four single-player games (not everyone had a friend with an Xbox and the game). Still, the franchise had two chances to redeem itself. The problem is: it didn't, and by the time Halo 2 arrived, veiling its trifling additions with admittedly strong online play, and Halo 3 imparted even less, it seemed clear that this one ought to go the way of the dodos.
Verdict: end
Crash Bandicoot/Spyro the Dragon - Does anything need to be said? These games haven't done anything in the post-PSX world except tarnish their posterity, already jeopardized by critical comparisons between either of them and the best 3D platformers being released on the N64 at the time of their heyday.
Verdict: end
Guitar Hero - I'm not so fervent about this one since it's not a game per the traditional sense: it seems to me that Guitar Hero could theoretically go on happily forever, introducing new songs to its canon and marginal gameplay adjustments (isn't DDR still around?) while hardly offending anyone. On the flipside, I would hardly describe the sales it's inevitably preventing of more worthwhile products as a good thing.
Verdict: indifferent
Grand Theft Auto - Some may differ, but my feeling was that Vice City felt like a rehash, characterized as it was by the map being reduced to "the strip" and '80s stylings not genuinely sufficing for significant gameplay changes from that venerated title, GTA III. San Andreas, to my surprise, didn't: it was expansive, and the ability to do things like swim, peruse three cities and boost stats made it feel something like the game VC should've been.
Mixed emotions set in, again, however with GTA IV: yes, the game's large, but after SA sheer largeness feels less revelatory, and the fact is the game represented a peculiar regression in many ways - number of cars, side-missions, etc. - from SA. As it stands, this series can still earn a second life, but it would take a risk to do so - say, a cel-shaded GTA set in Tokyo in the '50s, or some such thing.
Verdict: pending
Gears of War - The conceit was lame-o in the first place, and the fact the game could be said to be "categorically superior" to most things on the market (gee, that's hard) didn't mean it earned the sequel pass. Simply put: gameplay clichés like this may be worth a guilty spin, but they don't deserve a second. Or third. Or fourth.
Verdict: end
Legend of Zelda - LoZ: Twilight Princess hit lows not seen since Zelda II for the NES - and frankly, that's not good, for Nintendo or anyone. Of course TTP wasn't the first Zelda iteration that felt stale, atleast in relation to the series' history: after OoT, after all, Nintendo seemed to make the decision that nonillion new Zeldas would follow, all copying the same essential gameplay and featuring a new gimmick ("it's time-based and features shape changing!" "it's cel-shaded!" "you can be a wolf!"). Cynical, yes. But here's the good part: the series has a strong history, and the lead developer of OoT said recently to the media he wanted to top that title. So if he does - or produces something worthy of the franchise's best in the process - good. If not, then this one is due for a shelving, or atleast a reimagining.
Verdict: pending
Mario - There will inevitable be haters, fueled by the fact Sunshine was a giant misstep and the Wii lately is more ebb than flow, but the fact is Super Mario Galaxy redeemed the franchise, bringing to the table a game that was every bit as fun to play as Super Mario 64, if not as influential, and creating one - and there isn't many, after all - good reasons to own a Wii. The new concepts and refinements featured in SMG, however, represent franchise cred Ninendo should be careful not to burn, lest Mario becoming as prone to rehash as Zelda. To paraphrase Yahtzee: "where do you go after you've went to space?" The answer: the history books, and hopefully with no blemishes.
Verdict: stay