What is the difference between GmbH, UG, LTD ...

As you have already been told, the UG (haftungsbeschränkt) is so popular because it does not require a statutory capital of more than EUR 1.0. But before choosing this "cheap" legal form you should particularly consider the following:
For gaining some confidence in the market you should try to start with a higher capital. For the UG this capital has to be paid in total before the company can be registered. Because the UG is aimed to become a "real" GmbH you are legally bound to save at least a quarter of the company's yearly net income for raising the capital up to EUR 25,000.00 on a later stage. This then requires another notary act.
Therefore, if you should be able to invest some thousand Euro in the capital and see a possibility to reach the profit zone within the first years, the GmbH could become more attrractive:
Mainly, in the GmbH the profits can be spread without special regulations. Although it requires a capital of EUR 25,000.00 right from the beginning, the GmbH can be registered by paying only a quarter on every share and EUR 12,500,00 in total. The date for the payment of the rest of the capital can be determined in the articles quite freely. So, in some cases choosing the GmbH can be cheaper in the end and even if the UG by now is accepted in the market the Reputation of the GmbH still is remarkably higher. For getting some specific advise you can always contact us (www.lfr-wirtschaftsanwaelte.de)