Jak is more of an adventure series, with deeper characters, narrative, and much more effort is put into crafting the world they inhabit. As a platformer game, Jak is far superior (except Jak 3, which is more geared towards vehicles and weapons) to anything ever seen in Ratchet and Clank. But even Jak 3 is a superior platformer to anythign in the Ratchet series.
Ratchet and Clank with is almost entirely geared towards your jump button and then upgrading weapons while you shoot mindless drones. Ratchet and Clank has VERY underdeveloped platforming elements, it's more so a straight up action game where you go around collecting more money to get your guns bigger. Jak 2 and 3 have guns.
Jak 1: Almost entirely a platformer exploration item hunting game, lush environments, highly impressive graphics for a first gen PS2 game and even now (aside from polygon counts).
http://www.gametrailers.com/player.php?id=1754&pl=game&type=mov
Jak 2: Takes the game into a GTA esque sort of mold, but it keeps the platforming elements. One aspect that is VERY appealling about this entry is that you revisit locations multiple times, but with a new ability the scope and feel of the level FEELS different and plays out differently it's a real treat. Incredibly well done graphics, very well done characters and world. I cannot state enough how well designed the levels are.
http://www.gametrailers.com/player.php?id=1755&pl=game&type=mov
Jak 3: Jak 3 takes the series away from platforming a bit (though it still has more than say anyRatchet and Clank game and is better developed)and moves it more towards driving and guning sequences.The games does make use of some mini game sequences that are almost Ratchet and Clank worthy of deritiveness. However, overall, this is still a very very solid entry.
Jak X: A pure racing game, better than Mario Kart imo.
http://www.gametrailers.com/player.php?id=7509&pl=game&type=mov
The thing is, what you're getting with Ratchet and Clank, is not platforming at all, there are some undercooked elements of it in there, but like the puzzles in the game, they take the cognitive ability of a 2 year old to pull off. What you get when you play R&C up to 3 at least I haven't played 4, is a shooting game, 3 slightly tweaked and then improved rehashes of the same thing, with dull humor, dull character designs, very very undercooked level design and any other element in the game is barely worth even mentioning. You essentially get modes where you fight ships in your fighter, nowhere does this even approach the vision that of something like StarFox, nowhere can you even see any compitent mechanics built in to make it any fun, it's a mini games designed like the rest of the game, not on imagination or skills, but on having your guns bigger then theirs.
If you're going to get any R&C game just get one, you aren't missing anything in the other two that you won't get in just one. They're ok rentals, but really nothing memorable.
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