First longboard: 9'6" or 9'0"?

I bought an 8' Wavestorm and to my surprise I'm having a bit of difficulty standing up on it. I've attempted to ride it about 45 times now and I have yet to actually stand on it for more than a second without falling off. So I thought I'd try to rent a big old 11' longboard and see how that compared. It was easy. First try I rode for about 300' before the wave died out. As such I am thinking I need a board that's a bit easier to stand on until I get my skill level up. Knowing that I'll probably only have the board for a few months, if that, I wanted to get something cheap. I found an ad for a guy selling overstock brand new Hawaiian Beachboy Services (HBS) epoxy boards for cheap each including a thruster fin setup, and I can choose from one of about 10 different sizes listed here:
here:
I cant get the 10'0" board because they wont fit in my place so the largest I can go is 9'6". Thus it looks like the three largest options are:
- 9'6" x 24" x 2 5/8"
- 9'0" x 24" x 4"
-9'0" x 23" x 3.5"
I am basically looking for whatever is the most stable and easiest to stand on since that's all I am at in this point in time. Obviously the 9'6" board is the largest. However, it's only 2 5/8" thick which is much thinner than other beginner boards in that size range. I am wondering if the thickness is an important factor in stability, or if only length and width are relevant factors.
I am only 155 lbs, so all of them have way more volume than I need I think.
Unrelated, they offer a 10'x24" board in both a 3.5 and a 4" thickness. What's the point in offering two different thicknesses when all the other dimensions remain the same?
here:
I cant get the 10'0" board because they wont fit in my place so the largest I can go is 9'6". Thus it looks like the three largest options are:
- 9'6" x 24" x 2 5/8"
- 9'0" x 24" x 4"
-9'0" x 23" x 3.5"
I am basically looking for whatever is the most stable and easiest to stand on since that's all I am at in this point in time. Obviously the 9'6" board is the largest. However, it's only 2 5/8" thick which is much thinner than other beginner boards in that size range. I am wondering if the thickness is an important factor in stability, or if only length and width are relevant factors.
I am only 155 lbs, so all of them have way more volume than I need I think.
Unrelated, they offer a 10'x24" board in both a 3.5 and a 4" thickness. What's the point in offering two different thicknesses when all the other dimensions remain the same?