I've never posted, usually just read for an "FYI" type of thing, but this is what I do for work (aerial lift repair)
LRIII - Good solid unit, but cable drive upper boom. More cable maitenence. Altec requires drive cable replacement every 5 years, cable slugs will be stamped with a date. The same is true for the leveling cable unless they have a yellow stripe, then 8 years.
LRIV - Another quality product. If joystick upper control watch for saw dust build up in the linkage. Same for the hi-rangers
XT's - I'm soso on these. Good lifts, but the Altecs are more product for your dollar. XT's have tendency to wear knuckle bushings, which can be costly. Also have a problem with the weak basket bushings, which if let go can actually wear into the boom. Some thing to watch for. Also the joystick thing.
LR50 - Two words. Stay away. Older unit and Asplundh no longer owns the product line. Sold to Altec in 1991 and turned into the LR series. Mandatory retirement after 25 years, mandatory rebuild after 15 years, cable replacement every two years. If it is past the 15 or 25 year mark you will not be able to buy factory parts.
I see lifts of all makes, models, size, and age range everyday and I think one of the Altec not Asplundh LR's is your best bet. Depending on condition of course. Just my opinion, ultimatley the end user is the final judge.
Good Luck, Higgins