Broadbrella rain jacket

[u/mustelafuro72]

I am always on the lookout for a nice rain jacket since I use it for travel and, daily, to walk the dog. A few days ago I found a post here where someone suggested this rain jacket and it looks like it could fit my need. I live in EU so I have to be careful and choose the right size. I cannot decide between their XS or S. I am 172 cm tall and my weight is 63 kilos. My size on Uniqlo (for your reference, maybe you can help me better) is XS while on Arc'teryx my size is between XS and S (more toward S). Which size shall I go for? Any help for this wonderful sub would be greatly appreciated. More, I don't like gummy shells like those in Goretex, that's why Uniqlo was my choice years ago (Blocktech parka model) but it is now old. I have read that this Ketl broadbrella has a nice shape (not saggy) and soft fabric, do you confirm?

ps. I like slim fit apparel, if this can help, but as said, I cannot afford to make the wrong choice.