What Apple II to buy if not a GS?

[archm@pro-scat.cts.com (Arch Mirrielees)]

I am starting a search to buy a second hand Apple II for my son who has
reasonably intelligent children ages 4 and 6.  Like his kids, he and his
wife are computer illiterate, and I need help because I've never had
anything but a GS.
 
The intent is not for him to get tied up in a thousand bucks + worth of
soft and hardware at this stage since their children's computer acuteness
will not be properly honed for another 8-10 years (and yet there is a
strong motive to get them started as soon as possible).  The next decade
will be proper timing for him to make a major investment, thereby taking
advantage of any interim advancements, without flushing down too much
"green" spent in the meantime.
 
My thrust is for him to buy a second hand machine just below the GS level.
But I'm insecure as to exactly what to look for.  And this is the area
where I'm looking for help.  Thanks to Dan DeMaggio (and his FAQ) I've
rank ordered what _seems_ to be the best, with the best at the top of the
list, skipping all/any fancy stuff that could be included with a second
hand toy:
 
- IIc+ (= version 5 of the IIc's) *
- IIc (version 4 preferred over v.3) *
- IIe (enhanced)
 
* Find IIc version via BASIC and type "PRINT PEEK (64447)" and RETURN
 
And, of course, a color monitor is a requirement to help lengthen the
interest span of the children and take advantage of their educational
programs that will be coming down the pike.
 
Recommendations and/or criticisms to my thinking will be appreciated.
 
Arch