9 months ago:
None of these two episodes, to be quite honest. I think 5x05 and 5x08 were the best episodes of S5 which isn't saying much because the whole series was completely luckluster and pointless. Didn't like the evil!Gwen storyline at all. It dragged on for way too long, didn't advance the plot in anyway and in the end just became another abuse Gwen and then completely sweep things under the rug storyline. The only good thing about the evil!Gwen storyline was getting more Gwen screentime and seeing Angel's superb acting as a villain.
Instead of wasting 4 episodes on a storyline which didn't add anything to the plot, they could have been better served actually focusing on Gwen and Arthur ruling and dealing with everyday court matters. Maybe travelling to distant lands to meet with other royalty so they can work on uniting Albion. Having discussions about magic and dealing with tensions between those who wanted magic legalized and those who were against it so we could actually see why legalizing magic wasn't an easy thing to do and why Arthur and Gwen would be caught in the middle. So many things that they could have done to give Gwen more screentime and advance the plot. And yet this is what they choose to waste time on. Another abusive storyline. Like we didn't already have enough of that.
But if I have to choose then 5x09, I guess.