For me it is clearly visible, that the Fluke 187 and 189 came first with a very good usability:
+ only one button press to get to the secound function, e.g. set to DCV and press the blue button: VDC + VAC in 2nd display.
+ Quick Autorange in Ohm-mode
Then came the 289 and there were some very handsome improvements:
+ 2nd to 4th display with 60000 counts like the 1st display, not only 6000 (eg. DCV + ACV or min/max/avg dto. with peak)
+ better DC A, AC V and AC A accuracy
+ new 50 Ohm range with 0.001 Ohm resolution
+ new 100 Hz , 0.1 ms, 1 ms, 10 ms ranges, duty cycle 1 % to 99.00 % (was 10% to 90%)
+ new LoZ ACV 1000V range with 3,2 kOhm input inpedance against ghost signals.
+ 1kHz low pass filter for AC V + frequency
+ storage from 995 intervalls (707 can be event-driven) to 15000 events (only in the technical data, not in the specification of the user-manual)
Others remained or are only a bit different:
o same ranges for AC + DC V + A
o same burden voltage in A ranges.
o same or nearly same resolution and accuracy for DCV, resistance, capacitance, diode, frequency
(-) AC crest factor from 3-6 (full / half range) down to 3-5
+ but you can measure the crest factor in the AC ranges
(+) frequency counter sensitivity for AC A defined (but may be the same for 189)
+ frequency counter ranges doubled at same resolution (eg. from 50.000 kHz to 99.999 kHz)
(-) frequency counter accuracy is worse (from 0.005% + 1 digit to 0.005% + 5 digit)
(+) Max Capacitance increase from 50mF to 100mF
(+) VDC: CMRR from 90 dB to 120 dB,
- VDC: Normal Mode Rejection from 90 dB to 60 dB
- VAC: CMRR from 90 dB to 60 dB
- bigger size with 6 instead of 4 AA batteries
- display reading angle is as with most LCD display not good. Illumination is good for dark, but eats battery.
- weight from 528 g to 871 g
(-) size from 20x10x5 cm to 22x10x6 cm
and they introduced a menu with 4 function and 4 arrow keys and all that modern things.
This had some side-effects, which everybody who is using them dislikes:
slow boot
instead of one button for 2nd function
you must press the menu button and
select what you want with the arrow keys and
then press "save"
min. 3 Buttons and you have to look where you are.
The worse for me is the autorange: Autorange is microcontroller-software, slow like hell, eg. measurement of resistance or voltages in a circuit is annoying.
So while the measurement technology improved nearly everywhere from the 189 to the 289, the addition of the menu-driven microcontroller with software-realized menu and autorange is a pain in the ass.
I think it went this way:
Marketing: We need graphical display and modern menu driven user-interface
Development: Ah what you mean?
Controller: We take a cheap youngster from university and let him make the software.
Greenhorn with no experience in multimeter-usage or embedded software programming makes the software.
Use cases and "design follows function" were unknown, software was probably not modular, sparcely documented and when it works it was shipped.
This was the standard with the introduction of GUIs in embedded realtime systems in the 80's, not fluke specific.
Nobody got ever the standing or money to improve it.
So one of the handheld mutimeters with best features, accuracy and resolution has at the same time one of the worse user interface and autorange speed.
The reality is: there is no "best", everything has pros and cons. Therefore some multimeters with some aspects (here only hp and fluke, others have other aspects) :
fluke:
12 (size)
45 (2nd display)
179 (speed, easy to use)
87 V (field, if 12 to small)
189 (range, accuracy, autorange speed)
289 (features, range, accuracy, 2nd display DC + AC)
8060 (audio, 1 GOhm Rin)
8800 (20 V range with > 1 GOhm input resistance (std is max 10V with 1GOhm), nixie, just for fun)
hp:
3480a with 3484a (20ms autorange speed in ohm / DCV mode, nixie, just for fun)
34401a (accuracy, resolution, no fan)
34411a (accuracy, resolution, autorange / measurement speed, con: fan, price)
3446xa (accuracy, resolution, user interface, con: price, boot time, the 289 is fast boot against that, Windows CE, buildin µC flash ECC error for white front)
3457a (ranges, resolution, no fan, con: slow)
3458a (accuracy, resolution, con: size, price).