This post is 50% opinion because I haven't done all these things personally.
It depends to some extent on your mode of transportation and how much time you have.
According to this article, Imbros gorge is open year round: https://www.west-crete.com/imbros-gorge.htm Imbros doesn't have the length and I believe is not as dramatic as Samaria but it still a nice hike. You are essentially walking along a creek bed so most of the path is rocky, ranging from round small stones to craggy bits that you'll hike around (unless you have the agility of a goat : ) It would be an easy walk except for threading around the rocks. No climbing or scrambling is required.
After we hiked Imbros we drove on to Chora Sfakia and took the ferry to Loutro, and overnighted there. We loved Loutro - it's low-rise development on a human scale. The village(?) follows the curve of the bay where it's situated, with all shops and restaurants sea-side. There are hiking paths leading from Loutro particularly to the west, but we didn't have time to try them. If following this scenario it would be better to have at least half a day or a second night in Loutro so you can hike and swim there during the day.
Or instead of Imbros perhaps overnight (2 nights) in Sougia and take walks from that area. This website has some info on walks in western Crete:
https://www.west-crete.com/crete-walks-descriptions.htm
https://www.sougia.info/walk-lissos.htm
We didn't go to Sougia so don't have personal experience with it. It looks like a pretty cool place, though.