I'd go with Splunk for logging. For Syslog capabilities, Splunk wins outright from my experience. It's quick, very customizable, and there are many different modules some specific for vendors and devices. (Cisco Security Suite for one).
If you are really into SolarWinds and want to use them for Syslog then I would go with Kiwi. SolarWinds NPM has a syslog collector but under heavy load (a few hundred devices) it will get bogged down real quick in my experience.
If you are looking for normal device management then NPM, NCM, NTA are the way to go. You can't go wrong with SolarWinds.