Looking for good performance UPS

Hi, all,
I am doing product researching on UPS. Please provide help.
The requirements are as given:
1) able to auto-startup the server after power failure.
2) with serial port
4) manufacturer from taiwan, USA, singapore and korea are preferable.
4) We are using APC and Liebert now. If you have any better brand to recommend, please let me know.
5) if possible, i would like to have the contact of vendor as well.
Thanks.

Best Regards,
-oka oka-