Tyler,
I agree with the above response. If this is a dedicated “walleye” rod, I’d suggest going 6lb. If you want to use a mix of walleye and smaller panfish lures, then I’d recommend going 4lb.
Personally I really like using Berkley Nanofil in 6lb test. If you go with the Nanofil, please learn and use the recommended knots or you will be frustrated.
One drawback/benefit with Nanofil is it’s small diameter. On one hand the small diameter allows your lure to move very naturally. On the other hand, a small nick in the line is actually a big nick relative to the total diameter. I do like using it when inside my shelter but prefer a mono line when fishing out in the open.