ASI or War Caster for first feat? (Divination Wizard 4/Knowledge Cleric 1)

My rock gnome divination wizard recently leveled up to level 5 and I can choose between taking a feat and an ASI (I have a 1-level dip into knowledge cleric). I’m mostly looking to play a controller/debuffer in battle, so I’m a bit stuck since my spells require concentration (which War Caster helps with) but my save DC depends on intelligence.

Due to multiclassing requirements, my stats are a bit weird: 8 Str, 14 Dex, 14 Con, 17 Int, 13 Wis, and 9 Cha

So, should I go for an ASI or for War Caster (or maybe another feat like Resilient (Con) or Lucky)?