I'll address them as I played them-
2nd ed
Its where it all started for me (Sept 1989)   My first character didn't even get finished when he became a ghoul and my own party was forced to killl me. 

    My first DM experience as I ran Darksun for three years.   
2nd ed Player Options Rules
Enjoyed thourghly though several players characters all seemed the same. 
 
1st ed
More than anyhing else-  I will remember this edition for the freindships I started and still maintain.   
Homebrews that mixed / matched 1st and 2nd
Worked well.  Had a good time here also.
3rd ed
Moved our 1st ed game into third.   I found new awe and wonder within the game once more.
3.5 ed
EBERRON!!!!!!!!   In case you didn't notice.... I like EBERRON!!!!!!!
4e
Hoping to finally try it out this November at Carnage in the Mountains gamecon in Vermont
3.75 aka Pathfinder
I like the new revisions of the familiar.
Like some folks have already said-  Love that DnD.