Jeffl has some good points, your quality factors for the tool depend on what you have experienced. I like point tools, where the vendor does not saddle you with their unique personality too much. I think the following are common needs of the user:
1)ease of generating footprints and components as you need them, include a complete set of footprints separately. (getting around the library problem)
2)open netlist format so you can generate netlists from (eg.) C++ or check a netlist outside of the tool, or go to another tool.
3)availability on different platforms: Windows and Linux at least.
There are also some common complaints:
1)licensing software can take a lot of maintenance.
2)design rules are awkward and non-portable.
3)generating the gerbers and other files can be a chore in some tools.
@Karen, I must have missed the original comment about thermal management. I too think that some of these addons that adress things such as thermal management are very valuable tools. I have only found one low cost solution that has this feature.
"I'm really glad that I'm only responsible to enter the schematic. I have enough trouble just using the PCB viewer..."
Always had the luxury of an expert to do the Allegro PCB layout, I would sit with that person for basic instructions and later view the daily progress on the layout files. One thing I really liked was the ability to highlight a net on my Concept schematic on one screen and see the same copper become highlighted on the Allegro layout on the other screen. And vice versa.
Hmmm -- How about using a circle for each tool -- the diameter/size of the circle could indicate something (what?); and the color of the circle could indicate something else like cost, or ease of use -- what do you think?
Sure. You could also use a 3 axis diagram, and if you go for the circles, make them globes. Adding dimensions. Different colors could also be used for depicting additional dimensions.
Here's my $0.02: I'm an EE who got roped into doing PCB layout in addition to schematic capture, although doing my own board layouts has its advantages (speed, quality, etc.). I use Cadence Allegro for compatibility with our company tools; sometimes I do use our internal layout designers or do my own layout and have our internal dept. do the fab and assembly. My take on as far as ease of use goes is that the schematic capture part of the picture, called Capture, and inherited from OrCAD, is pretty darn easy to use; all the Windows-type (Mac?) stuff like ctrl-C for Copy, ctrl-V for Paste, Delete key, etc. are there, and to Move stuff you just click and drag. It's noun-verb, which I find very quick and intuitive.
Unfortunately, the PCB Editor for layout is a big, clunky program that shows its Unix command-line roots with a verb-noun interface in which you have to click on a verb (Move, Place, Add Connection, Delete, etc.) to get into the right mode and then choose the noun you want to act on. How dumb is it to have a Delete mode when there is a Delete key on every computer keyboard on the planet?! This abomination forces the user to do all Placement, then all Add Connections, etc. in order to have reasonable productivity. This really goes against the way I like to do things, that is, working on each section of a board and completing all actions in that area before moving on to the next section.
That said, I give Cadence high marks for support, although I've used Allegro long enough now (~7.5 years) that I haven't needed to ask for support in a long time (years, probably). OTOH, if the program weren't so hard to use in the first place, I wouldn't have needed so much support!
The last company I worked for from 2003 to 2006 used Zuken Cadstar, which had its own challenges, shall we say. I liked the noun-verb interface, but the worst thing about Cadstar was the serious bugs. On my machine only, I would get jumps in view at random times, IIRC when zooming in or out. Nobody else in our group of 4 or 5 had this problem. I did hear them cursing about other bugs, though, crashes probably. A bug common to all of our machines was the thermal relief "wagon wheels" that would sometimes be displayed and sometimes not.
I did see some bugs in Cadence Allegro as well. A previous version had instability that increased as the number of open PCB Editor windows increased: 1 window was good for ~1 week before it disappeared; 2 windows, maybe a day; 3 or more would only last for a matter of minutes! To Cadence's credit, I can't remember ever having a crash, due to either the multiple window instability or other reason, without a .sav file being available so that I could pick up where I left off. And with some versions I've seen the cursor position indicator go off-grid. These bugs are fortunately a thing of the past.
I understand that Altium is noun-verb and has a very nice time-saving feature of being able to apply a change to all instances of a type of object simultaneously. for example, it takes me a long time in Allegro to rotate reference designators to all the same orientation individually; with Altium, it's a single command. I don't know much about Altium, though, and it's a non-starter to get it incorporated into our company.
Now, some of our groups use Mentor Expedition in it's full form for schematic capture and layout, while others use DxDesigner for schematic capture and Allegro PCB Editor for layout. I don't know much about those products, but I do have to view .pdf's from the schematic capture program fairly often. The good: the .pdf's have some intelligence built in, and I can get information on a component by clicking on it. The bad: Mentor uses very fine lines in the schematic symbols, text, and wires, making it very hard to read without zooming way in and not being able to see much of the page. Cadence Allegro Capture, with it's OrCAD roots has a nice white background with blue, black, and red elements, making it much easier on the eyes. It even allows printing all colors as black to maximize the contrast when printing to a b&w printer.
My 2 cents that hopefully will be helpful to someone considering schematic capture and/or layout software.