The TextQuality property is relevant for RadChart which is obsolete. There is no equivalent for it in RadChartView. The RadGdiGraphics.DrawString method is used for rendering the text and it uses TextRenderingHint.SystemDefault. You can change how RadChartView renders its text by using the Windows ClearType Text Tuner and select the option that suits your requirement best. Please refer to the attached screenshot.
I hope this information helps. Should you have further questions I would be glad to help.