I have the 32 and love it. I use it 90% for grilling and almost always use it with the basket-splitter as it provides a great combo of high direct heat and much lower indirect heat. However, for me the preference for the 32 was driven entirely by the fact I'm regularly cooking for 25+. No doubt the 23 can do this as I did it solely on a '19 BGE previously. For big crowds life is much easier with the 32 and the trusty old BGE puffing away.
Having said that, if your goal is a couple of great steaks cooked to different temps, I'd go for the 23 all day long. One reason is the sheer size and weight of the 32. There's a whole lot more everything with the 32, including two 40+ pound grates to move when refueling.
Either way, you'll love it!