Based upon personal experience, Kenwood voice synthesizers are well designed and easy to use. They offer a unique and useful combination of (1) frequency announcements on demand, (2) automatic frequency reports after changes in VFO, band, and/or channel, (3) instant, audible assistance with menu navigation, and (4) announcements by the VGS-1 of the function keys and options.
Further details are here.
Also, other brands' have similar, modern, synthesizers. They are discussed here.