There have been a few topics on this exact question but basically (having a quality product and support is a GIVEN):
- Excellent established rep/history for host.
- Pro-active and very responsive support.
- Regular account upgrades.
- Well managed nodes.
- Well priced offerings
- Diverse options (OS templates, etc...).
1. Reliability -- I want a reputable hosting company that has been around awhile.
2. WHM -- I am developing my technical skills and WHM helps me in a wysiwyg kind of way. It makes managing a VPS easier for me.
3. A bit of hand holding. For me... a managed VPS is a must-have. Hopefully someday I will have acquired the skills to do this all on my own but for now... a little hand holding (or a lot depending on the issue) is a must-have for me.