Remote Central is an excellent resource for remote research - it is a very thorough resource with some truly exhaustive reviews of most every notable universal remote available.

What makes one better/worse than another? Some of that is a matter of personal preference. Since Jed M mentioned the Pronto, I'll use it as an example: some people are huge fans of the Pronto touch screen's degree of customizability and control, while other people prefer to be able to find buttons by touch without looking down at the remote and therefore can't get comfortable with a touch screen in place of a good hard button remote. (Like Jed M, I fall into the second category.)

The Universal Remote URC series are a derivation of their MX remotes - the MX remotes were never intended to be sold to the average consumer, which is why they are hard to find outside of web dealers such as BlueDo (who I think still has the best price I've seen for MX-500's). Rather than upset the custom installer market for which the MX was intended by changing the official distribution channel for the MX's, Universal created the URC family. I haven't used a URC remote, but from the reviews I've read it sounds like they are packaged and presented in a way that makes it easier for the average user to pick one up and get it working quickly for their system - a very useful trait in a universal remote. The MX-500, while perhaps not as conveniently documented (there's no accompanying DVD to walk you through the process like there is for the URC's, although the remote is quite good), is very flexible and is in my opinion the remote to beat in the sub-$100 or even sub-$150 or $200 remote market. It is an older design, but Universal has kept it up to date (including continual updates to the onboard code library, from what I understand) and the very convenient learning capability assures you of being able to cope with hardware that is rare or extremely new. It would have no trouble with a Tivo, and there are a tremendous number of people successfully using the MX-500 with Model 950's and Model 990's. I'd tend to stick with the MX's unless you spot a really sweet deal on a URC.

I don't know of a chart for comparing remotes, although it is an interesting idea. Among the Universals, I tend to boil it down to the following:

• MX-500 and MX-700 were the original two, with the 700 adding a computer interface, much expanded macro capability, and more memory (20 devices instead of 10, 4 pages of buttons instead of 2 for each device).
• MX-600 and MX-800 added RF support to the 500 and 700, respectively.
• MX-650 and MX-850 replaced the 600 and 800, with the only significant change being to the navigation pad (which went from a disc that handled all four directions as well as the center "select" command to a disc for direction control around a separate center button for "select").
• URC-100, 200, and 300 provided a "consumer" line.
• MX-350 is the custom installer version of the URC-200 (same remote, just a different name).

I'm not as up to speed on the different Harmony remotes, so I can't help with sorting them out among themselves.

I routinely recommend BlueDo for the MX-500 (just bought a two-pack of MX-500's from them - one for my dad's birthday and the other for my mother-in-law's christmas). My MX-700 came from an eBay dealer.

If you end up with an RF device in the future, I believe that there are devices that can convert an IR signal to RF, but the industry standard is still IR - a device with nothing but RF remote capability is very rare (the only one that comes to mind is a Bose unit, about which I shall say no more). In most cases, folks are using the RF capability of the MX-600/800 or the URC's as a way to control IR devices without having to aim at them or have the equipment in view.