For an introduction to affordable high quality eyepieces, you can't beat orthos. If you want to push your observations to the limits on faint objects then orthos are the way to go. I did some comparisons of my 5mm Baader Genuine Ortho vs my 5mm Pentax XW. The BGO had a very small edge in contrast but felt much harder work to use with the small FOV and short eye relief. The result is that the XW is my first choice in most cases. However, if I'm struggling to pick something out then the orthos come out. That's why there's a 9mm BGO that sits next to the 10mm Delos.