In springers, my experience is limited to a .20 HW95 and a .177 HW30, so I may be biased, but I'd think the HW95 or HW97. In my view, the .20 caliber feels slightly oversized for the HW30, which would result in loopy trajectory.
Zeroed the scope on the HW100 just in time for its first squirrel this morning. For the last two sighters, I had one eye on the target and the other tracking the fuzzy tail.
I went with these sportsmatch rings for mounting an Optisan CP 4-16x40 F1 to my HW95. They are dovetail rings and have a stop pin that fits the HW and prevents any creeping.
https://www.airgunsofarizona.com/scope-mounts/sportsmatch-et037c-2-pc-30mm-medium-extended-scope-mounts/?mobile=1
Received a CVLIFE BearPower 3-18x50 FFP and giving it a try on the HW100. Before breaking to make dinner, I got it mounted with dovetail rings and did a basic test of the turrets, parallax, and mag ring; everything felt smooth and positive.