Some go for aftermarket Dashes just to individuate their Bike, and here's nothing to add or to suggest. But If you're going to buy a dash due to the facilities is has, then you have to have a very close look, what the Dash is able to and what not.
A good recommendation is :
Make a list, what you'd like to have displayed, and/or Logged.
Try to evaluate, if you maybe will try to upgrade the System to a higher level ( I.E. Logging memory, or Number of Inputs/Outputs , or active Control of Relays or pumps or stepper motors, Injection , Traction Control, GPS...... and so on).

To summarize the Dashes on Market into3 Categories :

Kat I: pure Dashes with the usual Display-Features as : Gear, Laptime , Shiftlight
Kat II: Dashes which additional have logging capacities
Kat III: professional Computers, which are just Dashes "by the way". Those have usually a high Number of I/O's ( In-Outputs), and they allow to program nearly what you like, via tables which activate Outputs with voltages, Frequency , PWM or PPM and lead into stepper Motors, valves or relais or are used to work as Input into a ECU to control the Engine.

From Category to Category they're more and more expensive, and require more and more knowledge.
So- what you want ?

Category I: normal Displays

If they shall be of some kinda use, they should have first I high contrast.
An Information you cannot read fast ( on track ) is as good as no Information. So first Line it's important that you're able to read the RPM's very clearly and fast and with a good resolution. Next would be Shiftlight, which should be super bright , and a recommendation is that the dash should have at least 1 OUTPUT which you can configure as Shiftlight, to be able to use a 20 W Halogen " Beamer", which you'll even notice in sunlight conditions.
As far as I know all Dashes can be adjusted with a value for desired max.-RPM, but most of them start at 0 RPM as a fixed Value. In Germany we name that " sub-optimal" , as why should I bother with knowing that I've got 3 or 4000RPM now, when I've got a I4 600 ? More sophisticated Dashes allow also to adjust, where the Dash starts to show RPM's , means I.E: start at 8000 end at 16000. when you're below 8000 on a 600cc I4 you're to slow anyway.
Next is - does the Dash accepts OEM Sensors, so is it able to be calibrated ? Or do I have to buy special Sensors therefore, with another wiring an Location of the Sensors ? This can make things expensive and labour-intensive.

Kategorie II :
Dashes with logging capabilities.
a very difficult Field where you have to have a very close view not to stumple sometimes.
Essential here is a List to write down, what exactly you want, and what you may need/add in the Future.
The most popular Logging- aspirants are probably:

- Lambda-Values ( relative to TP and RPM )
Q here , is the Interpreter-Software of the Dash able to :
able to build a 3D Graphic with Lambda-Values relative to RPM and TP ?
And : what is the highest logging rate you can choose/ analyze ?

-Suspension : if you want to see things clearly, you need 500-1000Hz logging rate, because the velocities of the Suspensio can go up to 400mm/sec.
Q here , is the Interpreter-Software of the Dash able to :
extract the velocties, or just able to show the Positions over the Time ?
extract the usage of Positions in % relative to the riding-Time ?
generally - are overlays possible ?

- Wheelspeeds , good logging Rate would be 500 Hz.
every slide starts somewhere, and the very first Moment when the slide starts can offer a lot of Information.
Q here , is the Interpreter-Software of the Dash able to :
compare front and rear to create a new graph " Slip" ?
select the slip and to compare it with I.E. rear cushion velocity ( building a "scatter-plot" ) ?

Not so strong focused logging Aspirants :

- Oilpressure : can make Sense, 10Hz logging is enough
- Fuel pressure : I estimate that as important , because it can indicate relationships with Lambda-Values , I'd recommend 50-100Hz logging
- Brake-Pressure :could make sense to unveil Braking behavior or for active control of valves or relays.
- Clutch-Pressure/Clutch Lever Position : can makes Sense to activate Valves or relays ( Anti-Slipper Valves I.E.)
- Heat Detection of Tires : could make sense for analyzing of tire wear relative to temperatures ( and tire pressure ) , and for active intervention into traction control i.E.
- Lean angle Detection : at present I'm not sure about a proper Solution for that
- GPS : can make things extremely easy, can be used for Laptimes , track drawing, for acceleration/ deceleration values , also for corner-related intervention into Traction control settings .Max 20 Hz at present.



Category III : die professional Computers, which are Dashes just " by the way "


T give a rough Idea, what those Computers/Dashes (next to logging anyway ) are able to :

Such Computers do have 30 -200 fully programmable In -and Outputs , and ( depending on the used ECU ) they're able to have active control of Engine Management , they can calculate TC Settings depending on GPS Signals and/or Suspension Positions or velocities, can do automatically double-declutch via drive by wire or a valve.... or whatever you have in mind what you'd like to control or adjust.
Those computers work with tables you can configure as you like, Outputs which you can use as voltages or frequency ( PWM or PPM)
More you find inside Section :Motec