Seriously... OP doenst need app and doesnt bother abt OS. As per usability, Bada is the OS version of Touchwiz... all childish big images, simple setting. Its far far more easy to use than any Symbian 3 device. I have used C7 and, though its a wonderful phone with great display and camera, the UI is far too cluttered, difficult to get at first go, and certainly slower than Wave II.
And unless u want an android device with the facility of loads of apps and all, dont go for it. As a device, Wave has a faster chipset, stronger body, and better battery life than SGSL. Its lower memory, but unless u load it with lots of apps, u wont notice it. Plus, there wont be any updates for SGSL, Wave II will get the Bada 2.0 update, which is supposed to fix the app problem as well. Samsung App store is growing at a slow rate with relevant apps, but thats not a concern for OP.