In general I prefer a three cylinder anything to a 4 cylinder anything because it is much easier to balance the rotating & reciprocating parts in a 3 cylinder. The result is a smoother running engine. Sometimes a little bit smoother (less vibration) and sometimes the difference is very large. It does tend to be very large in favor ot the 3 cylinder when comparing with a two or a four cylinder configuration. When you tested these, did the Kioti 3 seem smoother than the TYM 4?
As far as turbo or not, a turbo adds both combustion efficiency and total HP when comparing same size engines. It also adds complexity and expense - but not too much. Turbos are well worked out and last a very long time.
The way for a manufacturer to get around a turbo is to make the engine a little bit larger - that takes care of the disparity in HP....just open the throttle a little more.
But the efficiency difference is harder to get around without a turbo. Basically the less efficient engine makes more pollutants and requires the manufacturer to upgrade the tractor's pollution control. That's easy to do, but tends to add back the money they saved by not going with a turbo.
In the end, unless you are using the tractor all the time at full throttle I doubt you will notice a difference turbo or not as long as the non-turbo engine is a little larger. Balance is something you will notice - but only you can decide if the tractor's vibration is important to you.
For me - and I haven't tried either tractor - I would lean toward the Kioti just because it is a three and the balance thing....and toward the Yanmar engine in the TYM because in general Yanmar diesels are really, really good.
good luck,
rScotty