To Introduce a Contrast:
* However
* Nevertheless
* Nonetheless
* But
* On the other hand
* Despite this
* Even so
* Yet
* Still
To Introduce a Qualification:
* Although
* While
* Though
* Even though
* Despite
* In spite of
To Introduce a Continuation:
* Furthermore
* Moreover
* In addition
* Also
* Besides
To Introduce a Summary or Conclusion:
* Therefore
* Thus
* Hence
* Consequently
* In conclusion
* Ultimately
More Informal Options:
* But anyway
* So
* Anyway
* With that being said
* Having said that
To Avoid Repetition:
* In the same vein
* Along similar lines
* To that end
* To this point
The best alternative for you will depend on the specific context of your writing. Consider the tone, the flow of your argument, and the emphasis you want to place on the following statement.