Originally I am going to say this one is a tie between the Eels and Weezer : they are both VERY hard-working bands, with members who know what it takes to be successful, and they both have some amazing (mostly happy/positive) songs and impressive albums!
I also like a lot of Pinback songs, and especially some of the members' side bands;
Rob Crow: (his name and one of his many bands) for the songs:
Forced Letter, Chucked, Taste, Scalped, Tranked, If Wade Would Call, and Purpose.
Rob's band: Optiganally Yours for the songs:
Gepetto, Night Shop, Held, Hope in Your Eyes, Pirates and Monkeys, and Bionic Whale.
Zac's band: Systems Officer, for their songs:
Stand Bye, Forever This Cyanide, Hael, Uhiju, Signature's Red, Sand 1 & Sand 2, and Oui.
Some of my other favorite songs include:
Alt J: "Lovely Day,"
Blur: "Good Song,"
Radio Head: "15 Step," "Reckoner," "I Might Be Wrong," and "Optimistic"
The Stranglers: "Golden Brown"
Karen O, Danger Mouse: "Lux Prima"
Foo Fighters: "See You," and "This is a Call"
I also like a lot of:
The Smashing Pumpkins,