I would go with something like mh or led if you want shimmer if heat is going to be an issue think about led or t5's. You could go with a combination of 3 mh and a couple t5 lights or get leds on a dimmer.
I am staying away from leds right now because they haven't been on the market long enough for all the research to come in and also the cost. I am thinking in 5 years there should be enough information out there to decide if I want it or not and the cost will come down.
Some people have great luck right from the start with leds. My luck probably won't be that good when starting with them.