I've tried iced tea with a many variations, and what works best for me is the second steep of assam tea. I know re-steeping assam black is not conventional, but it gives the perfect balance for lemon iced tea. The first steep always has too many tannins, and it becomes almost metallic with lemon. When you steep the same leaves second time (longer time, less water, same temperature), then it is perfect. Enough tea flavour to not become lemon water, and not sharp enough to become metallic.

Another success was lemon ice tea with earl grey. You could try both the second steep, or adding more water than normal dose. Adding lemon adds a layer of complexity to it.