At the risk of sounding too simplistic, it seems to me that the main propositions can be summarized in one saying.
这个原因可能较简单，不过，我认为可以用一句谚语来概括，________。 We may look into every possible reason, however, foremost reason for .... Is ....
其实有很多原因，不过，造成________的最重要的原因是______________。 It might also be noted that....
需要注意的是，____________。
Another reason why .....(凑字数，但不可滥用) is that....(有利于写长句) What is also worth noticing is that.... 值得一提的是___________________。
There is another factor that deserves some words here. 还有另外一个很重要的原因。 A more essential factor why.... Is that
________ 的更为重要的原因是____________。 A further reason why,,,, is that.....
________的更深层次的原因是____________。 In addition..此外，再者
Moving on to wider themes,_______
展开来说，_________________________。
The second thing that must be taken into consideration is that... 第二个原因也很重要(值得考虑)，亦即__________。 Likewise(同样), common sense tells us that... 同样，___________，这是众所周知的。 The third but very important reason is that...
第三个(尽管不是很重要)原因是______________。 The third, not the last is that, 第三个原因是___________。
The last factor to be taken seriously is... 第三个重要原因是_______________。
Finally, moreover, last but not least, furthermore.
As the proverb goes: 俗语有云：万事万物都有两面性。也不例外。 Every thing has a good side and a bad side, and ....is no exception. 万事万物有其两面性，而________也是如此。
The discussion as to whether the ... is a blessing or a curse arouses most people\'s interests. __________是好坏利弊问题引起了很多人的兴趣。
..plays such an important role that it undeniably becomes the biggest concern of the present world.
______ 尤为重要而引起当今社会的关注。 There comes a question: is it a blessing or a curse. 问题是：____是福是祸?
There is no denying that every thing has one more face and ... is no exception. 不可否认，每一件事物都有其两面性，其实，______也不例外。
Every thing in the world has its own two sides. Without exception, A has both advantages and disadvantages.
任何事情都有两面性，A也不例外，有其优势和劣势(利与弊)。 ....undoubtedly plays an increasing significant role in modern life. 不容置疑，_______在现代生活中不断显示出起重要性。
With the development of the society, ... is increasingly important. 随着社会的发展，_______变得越来越重要。 The merits of this is obvious... 其好处显而易见。
As we know, ... bring many benefits and convenience to people. 众所周知，_______ 为我们的生活带来很多好处。
There are no less than three advantages in .. as rendered below. 如下所示，_______ 至少有三种好处。
Despite the advantages ... has, some people claim, we shall not lose sight of its adverse effects on...
尽管_____有些益处(优势)，有些人则认为，我们不能忽略了其对______的负面影响。 However, like anything else,... has more than one face.
然而，象其他任何事物一样，______ 还有其它的方面。
However, with the advance of the human civilization, there is an increasing number of people who have raised doubts about whether...
然而，随着人类文明的进步，越来越多的人开始置疑是否__________。
Some people deem it is a dangerous signal and call for public awareness of the negative effects it has brought about.
有些人认为这是一种危险的信号，因此需关注其给社会带来的负面影响。 Of course, nothing in the world is perfect, so is... 当然，时间没有完美的事物，所以，________。 Despite its merits, it also brings some problems to solve. 尽管其也有很多优点，不过，也给我们带来一些问题。
But its bright side should not keep us from examining its dark side. 但是，我们不能因为这些优点而忽略了其缺点。
From the reasons presented above, I think the pros outweigh the cons. 从以上原因可以看出，其优势胜过劣势(优点多于缺点)。
As far as I am concerned, its disadvantages outweigh its disadvantages. 我认为，其优势胜于劣势。 总的说来：In general, all in all, on the whole , in brief, in summary, in conclusion, in short, in a word , to sum up, to conclude, to summarize,...
But all in all, I would say the advantages outweigh the disadvantages. With the advance of society, if we encourage the merits and eliminate the drawbacks, all people will enjoy a better life. 但是，总的说来，我认为其优势大于劣势。随着社会的发展，如果我们能对此善加利用，所有的人都能生活得更好。
From what has been discussed above, we may finally draw the conclusion that... 通过以上的讨论，我们可以得出如下结论，___________。 So, as I see it..
因此，我个人认为，_________。
What we must do is to encourage the strength and diminish the weaknesses to the least extent.
我们必须尽可能发挥其优势，趋吉避凶。
In conclusion, although ... has its negative effects, it can to a great extent bring us more advantages.