Formal:
* Therefore,
* Thus,
* Consequently,
* As a result,
* To summarize,
* In summary,
* To conclude,
* Finally,
* In closing,
Informal:
* So,
* All in all,
* In the end,
* Ultimately,
* To wrap things up,
* Bottom line,
* In short,
Creative:
* Taking everything into account,
* Weighing all the evidence,
* Putting it all together,
* Reflecting on the points made,
* Looking back on what we've discussed,
You can also use a transition sentence that directly relates to the main point of your conclusion. For example:
* "The evidence clearly shows that..."
* "This analysis suggests that..."
* "These findings have important implications for..."
The best phrase to use will depend on the specific context of your writing.