Like some of the above, I've been using a Panasonic DVR/DVDR for just over a year now and have really enjoyed it. The TV Guide isn't sophisticated, but it's very reliable and easy to use. I particularly like being able to edit on the hard drive and the archive programs off to DVD-R.
I have found that the DVDr is fussy about the brands of discs used. Mine goes into a coma whenever I use anything white.
I don't have any experience with Tivo, But I can recommenr the Panasonic.