Up here on my home waters, the 6wt would bethe light rod and it’s travel partner would be a 9wt (and that’s exactly what I travel with when space is limited).
I think an 8.5’ 4wt would be a good choice. I actually prefer a 9’ 4, but thats your call. If you expect to deal with the wind on a regular basis, I think you would be much happier with the 4 than the 3.
It’s like asking if someone prefers blondes, redheads, or brunettes? I built a 9’ 6wt. for bass and just love it. My brother hates the action, the length, and the fact that it’s pretty. ( Purple wraps overlaid with gold). I also have a 7’6" 4wt. for spring creeks where the length of cast is rarely over 15’. Build a relationship with a fly shop owner and he might loan you a rod for a weekend. Half the fun in life is the search.
I built that exact rod last spring and just love it. Has a little more punch than my 3wt and compliments my 6wt perfect. Now I just need the next step up. I have everything I need to build a 10wt but having second thoughts about a 8 or 9wt.