We're talking iconic/classic/popular for the brand, to represent it in a collection, right?
Not necessarily the nicest to use or "best" to modern standards, or the biggest/baddest they ever made, or most desirable to have today ...
I'd consider the likes of:
Stihl Contra, 08S, 026/260
Dolmar CA/CC, 112, 115/120(si), 123 or 133
Solo Rex?, 635/626-ish, 620VA-ish,
Husqvarna MS-70-ish, MS 90, 65, 254, 61/266
Jonsereds XF, 60/601, 80, 49SP
Partner R11/12-ish, R22-ish
Pioneer 620/650, P28/41-ish
Poulan 245A, 3400/4000, Micro XXV-ish
Homelite XL-12/XL Automatic
McCulloch 250, 10-10, Mini Mac-ish models
Oleo Mac (Olympyk) 250-series or Agristar
Alpina A-40, 0-70S
Echo ... dunno hard to pick ... the twins are iconic of course
just some other models to consider ...