Without being a smart a**, the best PPE is the stuff that you will wear. Make sure you get stuff you like and feel comfortable with.
HELMETS
Helmets should meet the ANSI standard. Most are rated for a single, top impact only. Some (Type II) are rated for side impact - they essentially have a styrofoam liner inside, but are bulkier and heavier. Husqvarna and STIHL all-in-one helmet systems are lighter weight - which many people find more comfortable and are more likely to wear. MSA makes some heavier duty helmet systems, which are also heavier to wear. The face screen protects your kisser, but does not replace safety glasses.
As noted, full brim keeps more rain off in the Pacific Northwest, where it is always raining. Not a big deal in other places. Climbers wear helmets without brims to avoid snagging, and with a chin strap to keep them from falling off. Some people find metal hats colder or hotter than plastic. They also do not insulate against electricity.
If you don't like the all-in-one design you can wear a standard construction helmet ($6), along with ANSI approved safety glasses (not just sun glasses) and ear plugs.
CHAPS
Again, more protective chaps are heavier and less comfortable. If you run a smaller saw, and are mostly cutting firewood from a stack, you might be fine with a lighter pair of 'apron' chaps (cover the front and sides of your legs only). 'Wrap chaps' (wrap around the back of your calves) provide more protection when you are climbing around amongst the wood, but are heavier, hotter, and more restrictive. More layers are more protective, but . . .
Most chaps are more comfortable with a pair of suspenders. Husqvarna and STIHL are widely available. A lot of guys on this site like site sponsor's Labonville chaps.
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OTHER
Don't forget boots!
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I have a few helmets and a few sets of chaps, and select them based on what I will be doing.
Philbert