Exchange Server - need reccomendation for good hosting company

I have a small business with 2 inside and 1 outside emnployee. I use outlook with a hosted,shared exchange server. I am having trouble with the company that is hosting, as they have had major service intrruptions lately.

I am wondering if anyone has any suggestions for this type of service. When it works, it works well, to a point. I have other issues but want suggestions first.

thanks