So, which is better: PS3 or 360? I've always been a PS guy, but I'm a bit jealous that the 360 has Oblivion.
Ah... the great question that only the
Console Wars(TM) can solve... oh wait. Can only muddy.

[Also note that Oblivion - with expansion pack - is available for the PS3.]
I'm tempted by the PS3 because it has blu-ray (even though I'm still on standard def, I'll eventually upgrade), but the X-Box looks like it has a lot more in the way of networkable games and profiles for multiple players. Even though I don't really like playing games on-line, I still like the idea of quickie downloads.
Xbox Live Arcade (XBLA) has tons (tons!) of downloadable games, ranging from $5 to $15. There's a lot more there than on the PlayStation Network (PSN), but also a lot more drek (so much so that MS is dumping a bunch that don't meet a certain criteria). The 'major releases' of downloadable games usually end up on both systems (eg. Street Fighter II HD Remix, Bionic Commando Reloaded). They each have gems (Braid on the 360; The Last Guy, Crash Commanders on the PS3); so it's a bit of a wash. IMHO, there are more games on the 360, but more quality on the PSN... YMMV. But with the 360, you have a better chance of finding something you like. [You do not need to pay for a Live Gold membership to get downloadable games - you just need it to
play online games on the 360. Online is entirely free on the PS3... with far fewer people calling you and everyone else a "homo".]
The PS3 also can do multiple profiles.
Also, what are some kid-friendly platformers for PS3 or 360? Is it basically the LEGO games or is there something comparable to Spyro/Mario/etc?
Little. Big. Planet. (PS3) Run - don't walk - to a store to try it out. This is probably one of the greatest platformers ever made - and it's for up to 4 players. Think of it as a Mario game if
Monty Python got a hold of it.
Spyro, Sonic, and the Lego games also appear on the 360/PS3.