I;m not sure if I am an intermediate but this is my experience so far:
I learned to SUP in Baja last month on an 11'4" Quattro (great board) plus some old narrower thinner ones I found quite unstable and was falling off of. Got about 5 sessions in and could carve a bit and go down the line in up to 6' waves
Rented a Kalama 11'6" in Tofino this weekend and rocked it in 4' surf, dtl and carving away from closing sections to ride the other hand section. This board felt big to me but it was incredibly stable (it is thick) I could not get thrown off it which was outstanding. It seemed hard to turn compared to the Quattro and I had to jump way back to the tail when starting on a steeper face and to carve. It paddles through whitewater very well and seems easy to catch waves but moves slowly until the waves gets decently steep.
So I'm guessing I can go to something a bit less stable and a bit thinner and shorter. I was looking at the starboard 9'8" extremist mainly because the starboard prices are so reasonable. And I will be wanting to surf it mostly so I am drawn to 10'6 or shorter. The 11'2 ultimate blend gets raves but maybe I will outgrow it in the waves? The C4 waterman and paddle surf hawaii look incredible boards but maybe out of my price range.
My main sport is kitesurfing and I am advanced in the waves so would be kitesurfing as soon as the wind is 15 knots. I think SUP is going to breath some new blood into me though, it's so fun and easy to catch waves. I couldn't believe the surfers were barely getting any rides and I was having a total blast yesterday.
Any input or experience riding the boards I mentioned here would be appreciated -
Re:first board to buy for intermediate? 4 Months ago
Aloha love sup, I had similar problem when I got started. I am experienced surfer who found SUP in waves VERY difficult at first. However, once I got good I had to change boards within a few months. So trying to find the IDEAL board at first is a challenge.
For someone like you I would recommend something in the 10' to 10"6", 27" to 18.5 wide and 4" to 4.5" thick range. The bonga from Southpoint is narrower(27") but performs very well in waves. The C4 is very good and so are several of the Surftech boards. My personal choice is Paddle Surf Hawaii boards from Blane Chambers. The best one is probably the 10"6 "all around" pop out. That board is plenty stable enough for the learning curve and can also be ridden in VERY sizable waves. Blane rode the same model in 20 foot faces at Ku Ikaika contest at Makaha this year.
I also advise renting/borrowing and testing as many boards as possible before buying one. Depending on where you live I can recommend a number of place to rent boards. Good luck and keep us posted on your progress!!