If you do not have the time, the best way to check out the travel agencies is at the Matta Fair since most of the players are there and you can compare their prices and itineraries. It is generally safer to go with the more established players. The fiasco with Excellence Holidays 2 years back should not happen again, hopefully. Among the big players, GTT tends to be the most expensive but I heard good feedback. I took a package trip to Turkey under Parlo Tours last year and it was very good but the whole trip in Turkey was handled by a local Turkish tour operator so don't know how the other tours would be like. I went to Greece under a two-to-go package under Sedunia Travel (in Wisma Genesis) and it was well-organised (again they were using a local Greek tour operator). For those package tours lead by a local (I mean Malaysian), I think a lot depends on the actual package and the tour leader or manager since his/her experience and knowledge of the places counts. Otherwise I believe they are more or less the same for the estabished players and the deciding factor will be the itinerary and the cost of the tour that best suits you.

I have gone on a few package tours arranged by local oprators here and all were using English mainly. Myabe you should clarify with them in the very beginning, before booking the tour. If you want tours that caters to 100% English speaking group, then you can try those UK based operators such as Cosmos, Trafalgar or Insight. I just tried one by Cosmos to Germany and it was well managed. Only problem, you need to make your own flight arrangement to and from the starting point of the tour. I don't think they have tours to China, though.