I would go with these: 40g breeder (36"x18"x16"), 50g (36"x18"x18", 120g (48"x24"x24"), or 180g (72"x24"x24"), though I feel a 180g would be too much tank for a newbie (such as myself).
-Notice how on the tanks I picked out, the height dimension never exceeds the width dimension, and the width dimension is always 18" or more. These dimensions will make the tank seem alot roomier, plus it gives you alot more variance in aquascaping plus room for good circulation. Remember, reefs in the wild are more like fields than bookshelves, so you want lots of width to play with.
-Research before you buy. Equipment is expensive enough as it is, and you don't want to have to find out 6 months down the road when you want to start keeping more delicate corals that you need a new skimmer that is 1.5-3x more expensive than your current one. Basically, buying good quality equipment in the beginning and sticking with it/ not having to change it out saves money in the long run and your reef is more likely to thrive.
Sorry about that, went of topic there. But basically I would go with 40g, 2nd choice 120g. Water changes would not be that big and good quality equipment not too expensive.
Good Luck!
