Our company started off implementing Siebel (The founders are all ex-Siebel employees). We recently decided we need to update our financial system and came across NetSuite. To say we were impressed with NetSuite would be an understatement. We replaced our financials (Quickbooks) and CRM (Siebel) with NetSuite and have been extremely happy. In fact we liked it so much we are transitioning away from Siebel services and supporting NetSuite as our main services platform. We just feel that having one system to manage your entire business is such an obvious benefit.
So with full disclosure on our biases I'll give you a rundown of my opinion on CRM solutions.

Siebel/Oracle (CRM On Demand) - overpriced, not worth it for small businesses. They need to rearchitect the entire solution from the ground up as it is basically a bastardization of their original client/server platform.
Salesforce.com - great marketing, not great functionality. It does have a lot of buzz, but I was just not that impressed.
SugarCRM - great product, I like the fact that it is open source.
RightNow - Decent product, I am not sure what there real business strategy is.
Saleslogix - Same as RightNow
Microsoft Dynamics - They have come a long way, but I feel they still have a ways to go. However, they are Microsoft, so you have to feel pretty confident in them.
NetSuite - Obviously I'm biased - see above.