Decided to go with cachy first.
Rufus and I don't get along. Amazon's search has always been horrible. If I'm inputting a particular model or SKU then don't waste my time showing me other crap that I wasn't searching for, or bury it on the 3rd page after all the sponsored links. Rufus was just more of the same. If I asked about a particular feature of an item Rufus would say something like, "I don't see that in the item description". I can read the description myself faster than I can get the answers from Rufus. Rufus is like some pushy salesman that doesn't even know much about the merch he's pushing.
Gemini was also horrible. It was one of the AI's that I tried when I was putting together the new computer system. Even just asking about features and specs of various components seemed to be beyond it. I'd been thinking about this build for several months and had already done most of the research so I already knew the correct answers. Google got it wrong so many times. I'd hate to have to trust it on matters where I didn't already know the answers. It couldn't even answer a question like "is X CPU compatible with Y motherboard?" I had a list of parts and I went through the whole list. When I got to the end and asked it to summarize and find prices for the items we'd "discussed", the list it presented even contained items that hadn't been mentioned! Links were broken. Prices were misquoted. Links went to items other than what was shown in the list. Again, more trouble than it was worth.
FWIW, the best AI in my test case was Grok. It was certainly more "conversational" in that even when I wasn't extremely precise in my questions it seemed to understand the intent correctly and respond appropriately. A couple times it suggested alternative parts that were cheaper or better than the items on my list, though in the end I only made one change from my predetermined parts list. It also seemed as we went along to get better at understanding the intent of the build and respond appropriately with that in mind when it came to making suggestions. It responded with sensible answers when I told it to give its reasoning behind its suggestion(s). A couple times it even asked me questions about why I chose one part over another. I'd like to believe that it incorporated my answers into its responses. Gemini would say things like, "that's what the people on the reddit forums seem to think". Great. I'm going to trust Reddit to build a $2K system for me?