I went with an interstate battery for my bike, they were cheapest of the 3 or 4 places I called. Can't remember how many cca it is. It's held up pretty well, but I also keep it on the battery tender when I'm not on it
So have you checked to see if your bike is charging at a good rate. A good battery should crank for some time. Maybe you have dirty throttle bodys or bad compression.
I haven't put a multi meter on it but my digital gauge says I'm charging fine. My TB is definitely dirty and I actually just pulled it off of the bike to clean and replace the rubber under it. I'm not sure how a dirty TB could cause this though. It's not that it takes a while to turn over. It's that if I start the bike multiple times in a row, the cranking power is dramatically lower each time.