I agree with the general sentiment that it's difficult to narrow this down to 20 for both films since Hasbro's coverage of them both in The Vintage Collection has been lacking.
I agree with the one note - any iteration of Dryden Vos is the best way to approach that.
ROGUE ONE
1 - Baze Malbus
2 - Bohdi Rook
3 - Director Krennic
4 - Admiral Raddus
5 - Mon Mothma
6 - Bail Organa
7 - Cassian Andor (Jedha)
8 - Galen Erso
9 - Saw Gerrera
10 - Edrio Two Tubes
SOLO
1 - Dryden Vos
2 - Tobias Beckett
3 - L3-37
4 - Qi'ra (Kessel)
5 - Han Solo (Numidian Prime - where Han wins the Falcon in the Sabacc game)
6 - Chewbacca
7 - Imperial Mudtrooper
8 - Argus Panox (The Lodge Sabacc game)
9 - Therm Scissorpunch
10 - Val (Vandor heist)
*This particular poll made me think that we also need a series of vehicle polls. And perhaps a creatures poll. I'm thinking we could break them down into the following categories:
-REPUBLIC ERA - Covers the PT, Clone Wars, etc.
-ERA OF THE EMPIRE - From Order 66 through to ROTJ
-POST IMPERIAL ERA - Just as it sounds - everything past the Battle of Endor
In the case of vehicles and creatures, I think that should be a Top Ten poll.