Gotta second Redskinsrock2689, I've been playing mostly Dante and Radec, and while they're good and pretty noob-friendly, they both have major difficulties:
Dante's supers are possibly the best in the game (perhaps second to Ratchet's), and his close range game is unbeatable, but he has only a couple reliable options for approach, and at range all he can do is poke, so a skilled keepaway artist can give him a very hard time. Compare to Kratos and Nariko, who have ranged command-grabs, good projectiles, and a whole host of good leap-in attacks.
For all ranged fighters (i.e, Radec, Drake, Sackboy, and Ratchet), keep-away is VITAL to his game (and will be more vital as people get better at hunting down campers), but Radec's keepaway game is pretty predictable by comparison. Your best options for keepaway are the laser, the electric grenade, and the shotgun/pistol combos, and people will know to expect them. The other three ranged characters have almost half of their moves devoted to mid range traps and mobility moves, so Radec can't really keep up with that.
What's this tier stuff about actually? I suppose everyone can kick everyones **bleep** if he takes enough time to get into a character so I don't give a **bleep** which character is "top tier" or whatever. But unfortunately the first character I ever wanted to play in this game (even long before he was actually announced) is Dante...but now all the kids seem to play him cuz he is "top tier" and looks "bad **bleep**" that really pisses me off -.-
Besides, I can beat all of those characters with my Ratchet any day of the week. (Not to say he's S tier, but that I play him well.)
For example, I play Big Daddy, who does really well against most of the characters listed in the OP, but loses abysmally to someone like Sackboy (Seriously, **bleep** that guy).
That being said, there are a lot of characters who look like they could be really good but we aren't running into much. FP and Dan are two prominent examples.