The war of the search engines rages on[line]. The differences between the engines aren’t quite so blindingly apparent in text based World Wide Web. However, these differences are more visible when searching the actual world.
Each major engine, Google, Microsoft’s Live, and Yahoo, have different source data, styles, and interfaces for both mapping and satellite imagery. They seem to vary in levels of quality, but for my purposes, I selected an obscure corner of Pennsylvania: Grove City College and the White House.
Satellite Imagery:Google:


Microsoft Live:


(White House is Censored)
Yahoo:


Grove City:
As you can't see (click the pics to actually be able to see), Google is a miserable failure. Live provides a sharp monochrome, but is distinctly out of date (two buildings built in 2002 are missing). Yahoo’s version is a recently updated and in color. While it may not be as crisp as Live, its other attributes make it the winner of this round.
White House:
Google is by far the best. Live is tragically censored. Yahoo is rather standoffish on this particular location.
Conclusion? There is no single "best" engine for aerial shots especially since they're all horribly out of date. However, I'm terrified of the day when these sites offer real time imagery.
Zoom:While both Google and Yahoo redraw the entire view each time the zoom level is changed, Live makes a smoother transition in and out. Furthermore, Live actually utilizes your scroll wheel / touch pad to decrease random clicking.
Pan:Meh. They’re all about the equal in terms of panning. Subjectively, Live appears to be smoother, whereas both Google and Yahoo render in “chunks.” Google smoothes out after you’ve been to a particular part of the map, but Yahoo stays choppy all the way through (relatively speaking). Yet, both Google and Yahoo offer a bonus feature: a mini map. For anyone that has played a Real Time Strategy game you know the value of the mini-map for finding things.
Search:Google uses one bar, just type the address or business followed by the city and state or zip. You can also ask for directions from this one simple bar.

Yahoo functions much the same way, except it has a secondary bar for the destination.

Live has two bars, one for the “business name or category” and another for the location. Note: if you want to search for a particular address, you need to put all the information in the second bar. Furthermore, it does not copy your initial position into its “directions” box. However, it was unable to pinpoint the address “100 Campus Drive Grove City, PA.” In its favor, Live does store your most recent searches right on the map though.

Pizza:This is by far one of the most important functions of any mapping service. For Google you search the map with another search (and you get 3,120 results for “pizza” with the map centered on Grove City). Live and Yahoo both give fewer, closer, results.
Yahoo has a handy little sidebar called “Find on the Map” which allows you to browse by category for community service (banks, doctors, etc), entertainment & shopping, restaurants (pizza is an option), and travel & transit (airports, parking, etc). All while leaving your original search location flagged.

Live also requires a second search, but because of their dual search bars, it’s easy just to type pizza in the first “business” bar. The detail is that it initially returned only three results, and worse yet my favorite option was missing. This is because when searching for a business without updating your location the default is to use the “current map view.” As you zoom outwards, more and more results appear.
Directions:This is a look at the interface for searching, not accuracy or ease thereof. Google is wonderful and allows you to enter your sojourn in a "POINT A to POINT B" fashion in the single box. Furthermore, it provides the directions in a nice table with the key points in bold.
Yahoo provides both start and end on the main page. Keeps on using Flash, but looks similar to Google. No copy and paste for you, well, unless you use the printable view.
Live wants you to copy and paste or retype your original location. However, it lets you pick any point on the map as your start / destination with a quick right click. Also, it does not trace the route on the map; it merely provides the points where you need to turn.
Note: Apparently, both Google and Yahoo use the same source for directions.Maps:Google and Yahoo are the same. Live has less contrast and is thus harder to read. Also, it has really tiny road names.
Right Click:Google: Does squat.
Yahoo: Tells you that you’re using Macromedia Flash 8.
Live: Gives you a handy drop down menu.
Address:Google:
http://maps.google.com/Yahoo:
http://maps.yahoo.com/beta/index.phpLive:
http://local.live.com/Cool Tidbits:Google: It’s Google.
Yahoo: Nothing of note.
Live: Has a semi-transparent search bar that lets you see a bit of the map through it. Also, it remembers the last place you were looking at and starts your questing from that location. And it has a button that says "Locate Me" and it can find you by your current IP address. AND it has a "birds-eye view" feature for selected regions.
Check out the White House.
The Results:| Aspect | Google | Yahoo | Live |
Satellite Imagery Grove City College
| 1 | 3 | 2 |
Satellite Imagery White House
| 3 | 2 | 1 |
| Zoom | 1 | 1 | 3 |
| Pan | 2 | 1 | 3 |
| Search | 3 | 2 | 1 |
| Pizza | 2 | 3 | 1 |
| Directions | 3 | 2 | 1 |
| Maps | 3 | 3 | 1 |
| Right Click | 1 | 1 | 3 |
| Address | 2 | 1 | 3 |
| Cool Tidbits | 1 | 1 | 3 |
| Total: | 22 | 20 | 22 |
The Breakdown:We have a tie. This isn't especially conclusive, especially if you look at the components of the score, you’ll see that Live gleens the majority of its points via nice flashy elements that push it to the eye-candy end of the spectrum. However, it really seems to be lacking under the hood (despite a nice Web 2.0 interface). So if I’m looking for directions from Point A to Point B, I’ll use Google. If I’m looking for a local business or restaurant Yahoo is looking pretty good, especially if I'm looking for it from orbit.
Each search engine has distinct inovations that continue to perpetuate the battle of the searches. This is an idea of the free market, multiple companies attempting to move their products closer to perfection through improvement, not price slashing (you can't beat free anyway).
Somebody other than me should take broad sampling for an in-depth comparison of the three in terms of Satellite Imagery. However, as of now, Yahoo seems to have the best images.