There is little to choose from between the Fox RLC damper and the Rock Shox RLT damper. Both are highly tune able and I can make them behave how I want them too. I don’t get on with Fox’s CTD damper but did like their RLC damper.
The thing that swings it for me is the dual air spring on the SIDs, the extra level of tuning really appeals to me but might not apply to everyone. You can make the SID more small bump compliant by putting a bit more air in the negative chamber.
If you are slightly competitive when racing then check which is lighter and go for that. Otherwise the SID just gets my vote, its slightly more adjustable and at a lower cost.
Where are you getting the SID from? I’ve looking around and can only find the newer solo air fork.