If you're looking to do soft corals in the beginning with mostly fish, I would consider getting like 2 T5s, since you don't need a ton of light for corals, but if you did end up wanting to upgrade in the future, it would be easy enough to just add another 2 or 4 T5s together, or use those 2 T5s as actinic supplements to MH or something. Lots of places to go.
Just make sure that if you do the 2xT5s that you go with quality first. I'm talking IceCap 660 ballast and IceCap T5 individual reflectors. Maybe even Tek. There are a million ways to do it. Just do it right the first time, going the extra mile and spending the extra dough, as it will save you upgrade headaches and walletaches later on.