Wow, what a loaded question... you might as well have opened the Chevy - Ford debate ( Ford all the way BTW)
My first tank way used VHO. I love the color spectrum output by VHO.
I had small tank with PC lighting.
My current tank uses 250W HQI MH with T5 Actinic. I also have some holding tanks with pure T5 lighting and one using NO flourescent.
If you must use flouescent, T5 is the way to go. I prefer the light output and the way MH lighting looks more that flourescent. There is someting about all the light coming from a single point that looks nice to me. If you haven't seen tanks lit with both types of lighting, you should find the time before investing in new lighting.
You will need to figure out how much intensity you want no mater which lighting you choose. The first variable is the color of light you want. The bluer the light, the higher the wattage you will need to achieve certain levels of PAR. Also the deeper you go, the more the light intensity (PAR) drops. If you plan on keeping a tank FULL of PAR hungry organisms, you will need a lighing system that can deliver high levels of PAR the entire depth of your tank.
For me, I wanted high levels of PAR to keep SPS but I also wanted areas of lower PAR to keep LPS and mushroom corals. I like my light to the blue side but not like full on Actinic blue. I have a 30" deep tank and selected 250W HQI for my tank supplimented by T5 Actinics. The fixture came with 10K MH bulbs which was too white for me. I switched them out to 14K bulbs and with the T5 actinics (which don't really change the color that much) my tanks lighing looks perfect to me.
Your best bet is to take a tour of tanks or tour of fish stores and check out some tanks with T5, VHO, PC and MH and see what you like...