I bought a road Angel plus last month and I'm very please with it, I can't compare with others as I've not used any, but the RAP has it's own batery, so no nasty cable, well not until 8 hours or so. It's also lights up blue so compliments the GTI interior.
You can switch off the voice warning feature (Tiff Needlel)

, and just have it pleep at you, or just have in flash, with no voice at all.