To be honest, l don't hit hard enough to play poly. My elbow, with poly tour pro, is starting to warn me of my bout with tennis elbow. I never realized that the 2025 ezone was so powerful that you don't have to swing at the ball. I'll try to "put the racket up to the ball" and see how it goes.
Good for you. If you know that poly isn't going to do you any good, there's no need to waste your time and money with it. Give your arm a break and try life on the softer side. There are a lot of options, but no need to get lost with sampling everything at two or three different tensions and keeping notes on all of the above. There's more than one right answer out there for you and you'll recognize a nice setup (for you) when you feel it.
I'm always recommending syn. gut (SG) around here. Multis can often be a bit softer, but many multi's can also degrade rather fast and individual sets of "premium" multi's can easily cost three or four times as much as SG's. If your #1 priority is to protect a sensitive arm, I'd say that a multifiber is a smart option, but many SG options bring moderate softness to the recipe that can play much less harsh than a poly and still perform really well.
A 16 ga. SG will probably behave a little better in a racquet with a 98" hoop or above that also has a relatively open string pattern - 16 mains with perhaps 19 or 20 crosses. I sometimes like to put a 17 ga. SG in one of my 97" or 98" frames because I'm a fan of the touch and feel of thinner string, but that can be a little more tricky in terms of getting the tension right. If lighter gauge string has too little tension, it can lose control for me rather quickly, especially when it's hot outside in the middle of the summer.
I also prefer 17 ga. syn. gut or multifiber in a racquet that has a more dense pattern like 18x20.
Syn. guts are not all the same. Prince SG with Duraflex, Gamma SG with WearGuard, and Gosen OG Sheep Micro are all too stiff for me to enjoy in a full bed, but some folks get along with them fine. Moderately soft SG's that I like include Babolat, Prince Original SG, Volkl Classic, and Kirschbaum, which is my favorite. Forten Sweet is a syn. gut that's extra soft - it can actually work as a low-cost alternative to some multifibers.
The square-ish shape of the heads on Yonex racquets can make them play a little "bigger" than other frames having the same head size in a more traditional oval shape. Whenever I've used a Yonex, I've preferred a 16 ga. string at a couple extra pounds of tension compared with an oval-shaped alternative frame having a similar weight, balance, and string pattern along with the same head size as the Yonex. Your mileage may vary.