When one of the kids or adults in the family wants to start fly fishing, we get one of the moderate fast Reddington 6 weight 9’, 4 piece all in one kits and throw the cheap fly line away and replace it with Scientific Anglers Mastery floating weight forward trout line. 5 weight rod is great for wet and dry flies, but 6 weight helps get a woolybuger or other streamer out there. With the 6 weight rod, dropping to 5 weight on the line can speed it up for aggressive casting in windy conditions or longer distances. With the same 6 wt rod, going up to 7 wt line casts streamers better. If the person really gets into it and wants a smaller or larger rod, a 4 weight pairs well with 6 weight and a dedicated 8 weight streamer rod can round out the top end.
If the wind never blows a 3 wt paired with 5 wt general purpose and 7 wt small streamer rod would be hard to beat. In windy states, starting off with a fast action rod isn’t the worst thing someone can do.
So much depends on a person’s preferences and casting style it’s hard to know what you’ll like in a year. It’s like picking a first rifle.