TBH its quite a personal thing, everyone has different shaped elbows and expectations.
I bought about 4 or 5 from CRC, tired them all on and settled on the POC’s. (Ive got 661Evos for my knees.)
The size is important, you cant go by the suggestions, you have to try them on. Once on I dont notice them, which is great. I now basically wear them for every ride as I cant feel them on. Overkill but my mate broke his elbow falling off on an otherwise safe bit of trail and was off riding for months.
Only downside is you cant bung them in the washingmachine, which is daft. But being elbow pads they dont get dirty like knee pads do.