#20 Lifestyles of the poor and unknown
19 Arnold's Tangled Web
18 Arnold's Initiation
17 It's Magic(guest:Ed "Too Tall" Jones
16 Street Smarts
15 Sam Adopts a Grandparent
14 The Trial
13 Health Club
12 The Wedding
11 The Peacemaker
10 Sam's Missing
9 Goodbye Dolly
8 Crime in the School
7 A Growing Problem
6 The Lie
5 The Fight
4 The Big Bribe
3 The Spanking
2 First Love
and the #1 All Time Favorite episode of Diff'rent Strokes is
#1 The Squealer
honorable mentions:Hooray for Hollywood,The Hitchhikers,The Wedding,The Honeymoon's over,Bed wetting,Arnold's Strike,Arnold's Bad Rep

my favorite episodes was The Hitchhiker and Bycycle Man.

I agree with Michael's list.