Tough to choose only 5!
I think the ideal number that pretty much everyone could deal with would be 24. But if only 5, then you need some variety with some short games vs long games, etc, etc.
Probably my blend would be:
SM - long game classic ritchie
MB - medium depth but lots of variety
AFM - classic layout with good flow & deep
CCC - continued software elevates
IM - short game classic Borg

Could also substitute as follows:
MM for AFM
Tron for IM
TF LE FOR SM
POTC for MB
ST Premium for CCC
Although all of this could change tomorrow...

Ok since the finally tally hasn't come up I want to revise my 5 to the following:
Tron or IM - too close to call
Met
MM
CCC
MB or SM - too close to call

As of right now today:
AFM or MM - an all-time great
MB or CC Continued - an all-time great
SM or ST - fun rules, good depth, challenge
Tron or IM - simple yet difficult, just one more
GOT pro or TF LE - all day depth
- - - - - - - -
NOTE : I reserve the right change the above lineups at anytime. Especially, if they do Star Wars LE right...

This week it is:

SM
IM
TF - or - GoT
ST
Tron -or - XMLE

Ok this week it is:
SM
TRON
IM
ST
TFLE

OK now a year later - out of my current lineup - my 5 would be (conceptually):
permanent members:
Tron
ST Premium
TF LE
IM
longer term games that could possibly rotate out at some point:
AC/DC Prem - or - Met Monsters Prem - or - AS LE
LOTR LE - or - SW LE

ok so now mine would be:
Met Monsters
ACDC prem
AS LE - or - IM
LOTR
ST Prem

Spider-Man is taking the spot of my SW LE!!!!
different strokes....

using this framework -
flow: ST or IM
stop and go: POTC or LOTR
complex rules: LOTR or SM
modes: AS or ST
Accessibility: POTC or ST or SM or ACDC

What about an all alpha-numeric awesome 5:
Taxi
F-14 Tomcat
Earthshaker
Funhouse
Bride of Pinbot

Let's see - only 5, huh?
Well today I think it would be:
LOTR
Tron
AFM
MET
ACDC

System 11 list of only 5
Taxi
ES
F-14
BoP
FH

Metallica
Ac/dc
Iron Maiden
Lord of the Rings
Spider-Man

Honorable mention: Iron Man

JJP DI
JJP WW
MM
Stern SW
Stern JP

Honorable mentions / Alternates:
STTNG
JJP POTC

current thinking is:
Met
MB
LOTR
MM
IM

been awhile but here goes:

Iron Maiden Premium or Metallica Premium
Star Trek LE
LOTR
TMNT LE
DP LE

ok revision of my listing:
ST
LOTR
DP
Metallica
Av:IQ -or- TMNT (this could be a rotation slot)

ST
LOTR (or Metallica Monsters Prem)
EHOH
AFM
DP

so today

monster bash
attack from mars
lord of the rings
star trek le
deadpool le