Thanks everyone, very informative.

I asked around at work as well and they gave similar responses:
The budget/entry telescopic ones are not that nice to use unless they are high end such as Mitutoyo which are much smoother
Three point internal mics are great but expensive
Verniers were not favoured in general (nick named Very-nears)
Two point internal mics were reasonable (as per 1st photo)

But critically, and as you mention Boyan, even with reasonable tools it comes down to the operator and the feel of the gauge when taking the measurement. This is something only experience can give - i.e. when the interference fit part just falls off under gravity you know your method needs a bit of work. I'm sure I can dial myself in as per all the other tools I've got.

In all I'm homing in on the 2 point internal mic. Reasonable price, just one measurement to take, seen them used a bit (Youtube etc.) to make good parts. Maybe one for the Christmas list . . .

Thanks again