What's the sweet spot for 11s cassettes and chains?

[Smitty2k1]

I've got a Shimano 105 R7000 groupset on my Black Mountain Road+. It currently has an 11-30t cassette in the rear but I'm finding myself in the 30t cog for climbing pretty regularly. I think I'd like to move up to an 11-32t cassette on my next chain swap, which should be happening soon.

What do you find to be the sweet spot for cassettes and chains in terms of series/level/cost? Should I just stick with a 105 R7000? Any reason to splurge on an Ultegra or look at SRAM offerings? Any pros or cons to mixing and matching?