Choose which group each word or phrase refers to

There are different reasons why it, There are several explanations for, There are many positive/negative reasons for, There are some/more/fewer benefits/disadvantages to, I believe, I'd like to explain why, Personally, I'd enjoy, I would prefer, I think, In my opinion, As far as I'm concerned, It seems to me, I suggest, First (of all), Second ... Third, Firstly ... Secondly ..., Thirdly, In addition, Similarly, Furthermore, Moreover, Further, In conclusion, Finally, As a result (of), In summary, Therefore, To sum up, In other words, To summarize, In brief