Nitchia is the consensus favorite in terms of quality and bulb life. The problem with Nitchia is that it can be prohibitively expensive and the difference in performance vs. other brands doesn't typically justify the expense. Cree is a favorite in the US because it is American made and they perform their own encapsulation, therefore controlling the entire process. In actuality, if you look at the statistics behind Cree bulbs, they degrade at a faster rate than almost any other brand. In fact, most colors degrade over 10% in the first year! Color uniformity in Cree is, however, very good. Silan is typically the cheapest brand available on the market. The reason that Silan has a bad reputation for quality, aside from being made in China and the implications of the China brand relative to quality, is that Silan does not encapsulate their own semiconductors.
Instead, encapsulation is performed by daisys third party companies which may or may not be using suitable semiconductors and may or may not be doing a good job. This means that when it comes to buying Silan, the most important aspect to look into is where the Silan semiconductors are being encapsulated. When you compare the raw data on the semiconductors, they actually outperform most other brands. Their red LED's in particular have phenomenal performance but the brand becomes unreliable due to the lack of control they have over the rest of the supply chain. There are several Taiwanese manufacturers that do a great job of controlling their quality while also providing a low cost product. This is where the best values are found. Among them are HPO and Epistar in particular. HPO is a great choice for high brightness applications like message centers where the brighter the bulb, the better.