find myself doing the same and have been giving this a lot of thought as to why:
chat won memory first. i think this instilled in me a lot of personal interactions, questions, and long-term goals, so i knew my go-to “guy” would end up being chat. almost like having a childhood friend, whereas claude is more of a “work” friend who knows what i am currently working on.
claude code cowork design the default of using the desktop app makes me much less likely to use claude for quick personal tasks on my computer (still figuring out the exact reasoning, but again, i think it is the general association with work that prevents me from asking random questions like “who holds the longest jeopardy streak” to claude).
the mobile experience on chat feels cleaner. the haptics, the audio, the polish of the swift ui just wins.
i have no idea why or how this happened, but i use ChatGPT for personal and Claude for work.