your question is way too broad. The Pa800 has features that the PSR3000 does not.

Ask your self the following qurestions

1.Do i experiment with sound creation on the keyboard or assisted by software programmes on computer or rarely if at all ?
2. am i into sampling or would i like the option to do it onboard the instrument
3. Do i write original music and if yes do i want to crfeate detailed songs onboard the instrument or do i use an external sequencer ?
4. Is ease of use really important to me ? Are you familiar with the korg and yamaha operating systems ?

Once you have addressed these questions it wil be easeier to advise you as to which instrument is more suitable for your needs