I have 105 pedals. As far as I can tell there is barely a difference between 105 and ultegra. They seem to use the same carbon body and I think the only difference is Ultegra using a different steel alloy for the axel, saving 18g. Depends on you if you think that’s worth the extra 25 bucks or so.
oh just be sure it’s the latest r7000/r8000 version… there are still a lot of the cheaper old r5800 on the market. They have a steel body as opposed to carbon, which obviously adds quite a bit of weight.