I selected d20Pro because that is what I happen to use. I have briefly tried some of the other fine tools, and I explain below why I ended up continuing to use d20Pro after sampling the capabilities of several free and proprietary tools.
With the advent of 3E, I started using DMGenie when a friend mentioned it because of:
- Electronic character sheet with the ability to create weapons, armor, etc. (builders), add mundane and magic items (had weights, costs, charges)
- Combat effect tracking including extensive mundane, magical, situational effects and durations
- Ability to apply modified attacks against modified defenses for PC's, NPC's, monsters, etc.
- Campaign manager with hyper-linked text and maps, including links to...groups of monsters, treasure, etc.
- Electronic reference capability for searchable text of skills, feats, powers, spells, etc.
- Calculators for generating new PC's and creatures, leveling/advancing, templating, random treasure with adjustable frequencies of types
- Scripting of effects, feats, etc.
- Creation of custom content; import/export of individual and mass "things"
- Time tracking (custom periods/months); weather generation based on climate, etc. and changing as you advanced the timer
I mention this list of capabilities because I do like rules, and simulation. I have DM'd 1E and 2E, and with the availability of computerized game aids, I jumped at the (to me) more consistent organization of game elements in 3E. This tool helped manage that.
Having said that, one thing that bogged down was continually cross-referencing during actual game sessions when players were attacking and damaging monsters, and vice versa, because there was no adequate tactical overview map to represent creatures, structures, and items as tokens. We used dwarven tiles and miniatures, and I needed to effectively indicate what creatures were in what states of disrepair. Custom circular cardboard counters set under the miniature bases helped for effects, but damage took more time.
Gaming with new players in the group who mentioned modern VTT initiatives and approaches spurred me to consider a way to streamline more. But to be clear, another one of the newer players much preferred physical dice and was not sold on the VTT experience despite being a very avid WoW'er. I looked at VTT's and bought a projector to beam color gridded maps onto the table where miniatures could still be moved. That was short-lived.
We transitioned to completely VTT play, whether at the table in a LAN configuration, or remote--including hybrid for some members concurrently.
So I briefly tried some other very fine VTT's. The reason I started dinking around with d20Pro and ended up using it extensively included these reasons:
I was doing something within minutes the first time. I opened a gridded map. I pulled some characters and a monster onto it. I right-clicked with a PC and chose a weapon attack. A circle with a line from the character let me drag it to the monster. The attack roll was high enough to overcome its AC. There was a thwack sound, a grunt, and some red moved up the 2D counter pic.
So this ability to show damage in multi-opponent combats (and effects, etc.) was a huge time-saver. Everybody not only knew where everything was positioned, but they could make more effective tactical decisions quicker. There were templates that auto-applied damage and auto-rolled saving throws.
So in a group that likes larger combats, things sped up dramatically.
I like that the DM can tweak to a fine level of detail the exact attacks available, the damage types (incl. energy) and so on. Such can be resisted by damage and energy resistances (partial or full) and combinations. Abilities can do many things including modifying stats and skills by types (luck, morale, enhancement, etc.), heal or damage, with saves, and so on.
Things I would like improved include automatically changing spell and ability effects such as when leveling, or other types of modifiers due to other spells or putting on/removing magic items.
In summary: I like complex, organized factors that allow for tactical combat simulation for a 2D/3D turn-based representation. I want the factors to be initially available as building blocks, and to have any effort spent re-usable. (Once you configure a monster, you can just drop one in later, again and again, with the necessary attacks and abilities configured).
I want the virtual tabletop situations both in-combat and out-of-combat simulation to flow. Each player moves their character(s) around, controls NPC's (animal comp., familiar, summoned). They advance toward pictures of buildings, cave entrances, pools...whatever. There are other counters that might be hidden which suddenly appear (aside from fog of war, etc.). [Oh yeah, using tiles is awesome, but it is difficult to represent large scale areas, or switch back and forth, etc. Virtual maps very much allow for those capabilities. Because you can zoom in and out and set the grid size when importing a map, you can create adventure maps representing hundreds of feet for long-range simulations.]
This tool allows for those things. There are various windows that can be moved around and stacked. On my dual-monitor setup, I fill 1.5 screens and position the initiative roster, the tools, the library, the random die roller, and the log around and move and resize the map in the center. The graphic map is the focus of my attention and is often the largest thing before me, in full color, with the players and other creatures available.
Streamlining the simulation aspects allows me to more often provide narrative elements, challenges, and other non-combat options during the hours-long game sessions.
Other DM's and players will of course run the gamut in preferences for e-tools (if any), how much automatic calc'ing is allowed (more like a CRPG), etc. This is my experience, and I like it. None of my new or veteran friends/players have uttered a single complaint, though we agree there are things that could be improved.