OK, my list is long, and I even trimmed it down! :-) Let's face it, any ep with Sam is one I love! lol I know some of these may not fit the usual list of Sam-centric eps, at least according to Dean girls :-) but they're all ones that stand out to me as "Sam eps" I love for one reason or other:
Pilot
Wendigo
Bloody Mary
Home
Everybody Loves a Clown
Simon Said
Playthings
Born Under a Bad Sign
Heart
All Hell Breaks Loose
Bad Day at Black Rock
A Very Supernatural Christmas
Mystery Spot
Metamorphosis
I Know What You Did Last Summer
After School Special
The Monster at the End of This Book
When the Levee Breaks
Free to Be You and Me
Sam, Interrupted
The Devil You Know
Swan Song