There are some really cool looking pendant lights that look outstanding. As far as T5 vs Halide either one will allow you to grow just about anything you want in the tank. You have a lot more color choices with T5's but the pendant size will be larger because you will be using more tubes to get the same amount of light as one Halide. The Halide T5 Combo fixtures give you the best of both worlds allowing the intense Halide light and the ability to tweak your color choices with the T5's.
If you use a pendant light consider how you will run the power cord. In my opinion the power cords can ruin the clean look of a pendant light if not hung properly. If money is no object there are some really cool LED fixtures out there. Because the LED light focus the light straight down you can mount them higher above the tank and still illuminate only the inside of the tank. These new LED Fixtures give you unlimited color choices and intense lighting but you better have deep pockets.