I used the FiOS DVR for the better part of a year before I got the TivoHD.
My two biggest reasons for buying a Tivo were (1) Verizon's unreliable guide data provider, and (2) limited storage capacity.
With its Motorola boxes, FiOS currently uses a cheaper guide data provider whose program information is not nearly reliable or comprehensive as TiVo's. On average, I missed several recordings per month with the FiOS DVR due to faulty guide information or improperly flagged shows. I have not missed any shows since upgrading to the TiVo. For me, reliability is the best thing about the TiVo.
The FiOS DVR has a 160Gb hard drive (20 hours HD) and cannot be upgraded or expanded. The TiVo supports external hard drive expansion. With the TiVo, you can also upgrade the built-in hard drive. It took me less than 25 minutes total to upgrade the 160Gb drive in my TivoHD with a new 1TB drive ($110
) which gave me over 150HD hours and 600 SD hours of capacity.
The TiVo has series recordings like the Motorola DVR, but it also does something that the Motorola DVR can't -- content based recording. The TiVo can be set to continually search every channel you receive and record all content -- regardless of date, time, and channel -- matching certain title keywords, keywords in the description, actors / actresses in the movie, directors, or subject matter. You can combine any/all of this criteria into a single autorecord search; you can make certain keywords or actors required, optional, or excluded. Here's a screenshot
of my autorecord "wishlist" search for presidential debates; the items in parenthesis are used to indicate OR. Here's another example
which I use to record all Washington Capitals hockey games, regardless of date, time, and channel.
There are plenty of other differences, of course. Menu navigation on the TiVo is more intuitive. The TiVo supports high-definition multi-room [DVR] viewing so you can view HD recordings from your Living Room TiVo on your bedroom TiVo. The TiVo allows you to download SD and HD recordings -- in full resolution and quality -- directly to any computer over your home network, which you can then burn to DVD or Blu-ray. The TiVo will let you view photos and listen to music stored on a computer in your home. The TiVo also lets you schedule recordings using a mobile phone
The only areas where the Verizon DVR outperforms the TiVo is in (1) channel surfing and (2) VOD. The TiVo DVR does not support FiOS' VOD. The Verizon DVR is also better suited for channel surfing than the TiVo. The TiVo is really designed around recording and viewing recorded programs. Guide navigation is a little slower on the TiVo, but DVR function response (pause, replay, fast forward, 30s skip, etc) is much faster on the TiVo. As long as most of the programming you watch is recorded, you are going to be thrilled with the TiVo.
Note how multiple episodes of same series are grouped; the episode titles are listed inside each folder. The folders with stars contain programs automatically recorded across multiple channels with boolean search; these folder names are fully customizable. Without such grouping, a DVR with 1TB capacity and dozens of recordings would quickly become cumbersome.