Im not running either at the moment, but I did LOVE my MH HQI pendant when I had it. As rob mentioned I really like how the bulbs has a gradual build up to its maximum brightness/wattage. Gives the animals in the tank enough time to adjust. The shimmer a MH creates looks more natural on the sandbed then any other lighting out there.

Although ive not had T5 (yet) what I do like about them is the wide variety of colors spectrum to choose from. What I do not like about them is that they do not come in longer lengths.

I run 3 60" VHOs on my 180 and can not be happier. Run PC on my biocube. Call me old school in that way, im ok with it ;) If it works, looks good to you and you are happy nothing else matters. I apply that thinking to everything I own.