HI Dogstar - OK, here's my input:
Bigger is indeed ALWAYS better, because the more the water volume, the less strict the maintenance schedule HAVE to be, AND the tank as well as it's inmates are far less impacted by ie. a fish dying, or perhaps extra wasted food lying around rotting.
BUT - it is also FAR more expensive to get to a level that you will be happy with...
The Boyu TL-550 seems to be a very popular choice these days....
The only restrictions I would suggest you might have, and end up trying to modify, are:
1) the lighting is not really enough to keep corals in - some soft corals might be ok with it, but most corals not
2) you can NOT even TRY and keep an anemone happy in the standard lighting
3) the unit comes with ceramic noodles and bio-balls, which is best removed - as it just ends up creating a problem with too high nitrates
4) the little skimmer is a nice addition, BUT will NOT work for a reef aquarium..... it does not really work as expected....
5) the small water volume means you WILL most likely end up being forced to do at least weekly water changes (at least the amount of water/volume of water you have to change at a time is not much - something like 6 to 10 litres at a time)...
Other than the above, the Boyu is a good choice.....
Good luck mate...