I can speak to Solarwinds Orion's direct comparison to LMS 3.0.
1. Scalability. In order to manage 10,000 Cisco devices in Orion you'd need 25 beefy Windows servers, LMS 3.0 you need 2 (Solaris or Windows)
2. IPSLA Nothing in Orion compares to IPM.
3. Cost (you costs will vary depending on your agreement with Cisco or Cisco sales partner. Orion was quoted to my organization (a current customer of Engineer Toolset with over 30 seats) for a software only cost of 1 million dollars US.
4. Focus. LMS 3.0 is a Cisco only element management system. Orion tries to be a MOM (manager of managers) soup to nuts.