IMO Windy is more user friendly as it gives more info at a glance.
But both Windy and Windfinder are only accurate about 24 to 48 hours in advance, you can see some real changes displayed as you get closer to your planed fishing day.
You need to know how to pinpoint the location you plan to fish as much as possible on the maps.
I usually don't commit till the day before, weather conditions are so unpredictable due to our two big lakes.
Put it this way. I have to go up in a man lift near the end of this week to work on two solar units (48 panels mounted on a 21' mast, dual access).
According to Windy i'm good to go only on Friday, Windfinder shows I have Friday and Saturday. I'm hoping Windfinder is more accurate, but the man lift won't be rented till the day before... so much like fishing, only I'm the fish watching the jig go up and down.