This depends on three factors:
2. Size requirements (and available space in the case)
3. Performanc requirements
1. Raid5 will yield better storage/dollar ratio... so is better for budget.
2. Raid5 "wastes" fewer drives, thus yielding more storage / drive bay slot (same as #1 really)
3. Raid10 is much faster for WRITING performance, and a little faster for reading.
Having dealt with virtuozzo vps servers on a large scale, I can safely say the writing I/O on a vz server is usually pretty low.
In short, your best bet is probably raid5
That is what I have always done on my VZ machines :-)