They also strongly advise against an 18 ft. or 19ft as the wind seems to dominate those boats. It seems that people with the 18 or 19 ft. boats are selling to upgrade to a 20 ft. boat. I would rather spend a little extra and get a boat that i do not want to upgrade right away. Thoughts here?
Who is "they"? When you start asking for opinions about boats you are going to get responses from people who think theirs is the best and from people who made the wrong choice, with the probability of any of their choices them suitable for you 50/50 at best.
Boat length has little to do with the effect of wind. The effect of wind on any boat is going to be affected by the height of the sides and anything that you may have sticking up, t-top, bimini, etc.
Lighter boats are going to be more maneuverable. It takes more to get a heavy boat moving and you don't have steerage without water moving over the hull.
The main reason people want to move to a 20 footer is space. You also have a lot of control over that by finding a boat with a layout suitable for the kind of fishing you are going to do. Room is subjective. I have fished four people in my Seaark 1872 CC with tackle boxes and coolers and no one got in anyone else's way.
When I was looking for my first boat, which was a sailboat, I had aspirations of cruising off into the sunset at some point. I was told by a vey wise man to buy what I needed to meet my immediate needs and worry about the what ifs and maybes later because they may never happen. He was right, I never sailed away but I did have many enjoyable days and nights on the lake.
Look around and try to hitch some rides with owners of different boats. hey will be quick to tell you if there is something you should be wary of, then look for something you will use now. With a $15 budget, there are some pretty good deals out there. Take a knowledgeable friend with you and don't buy anything without a complete inspection. A survey is not that much money and it can save you a lot of grief.
I didn't mean for this to ramble own, but I've been in the marine industry for a long time and have seen a lot of stuff go down. Know what you are looking at.