Jesse i have those at school and don't reach for them because they sound better , it's not that , most are on pair with what we can have native and i 'll get some native other them quite several time ....the key is the respect of audio source , UAD plugins are all pretty heavily oversampled internally , so you'll get a constant quality and dsp off your omputer cpu (noticed that i does take some native cpu as well) .
So for me UAD is a waranty of
1) Processing no matter how crappy is your computer power
2) Quality of processing .
The plugins that impressed me were the ocean way (witch ik sunset answered the need of getting it) and the UA 176 /175