I can say for sure the one that was most obvious to me from the basic swaps was the 4.0L t/b and high flow filter, i did the gearing long after so i can't compare the 2, they both yield gains or seat of the pants feel, on the 4.0 t/b and airfilter was that i was actually able to see some speed increase in 4th (with the stock 4.10 and 33s) whereas before it was a constant shifting between 3rd and 4th on any slight change in wind or even the slightest uphill - that's what i remember anyway. Of course a week or so later it felt like nothing was changed, but so it felt after the gearing change, it's what you get used to as there's no metrics to really gauge the increase (feel vs some numerical dyno results)
the other thing that shadows any gains is that highway speeds, wind and hills (by the means of no aerodynamic considerations, large frontal areal, lift that adds to this and also weight gained by adding armor, whinches, larger tires/wheel, roof racks, etc) are really the ones hurting us the most, since a 10% increase in HP would probably mean a 1 or 2 mph increase at top speed you'll rarely see the benefit in it. On the other hand with the gearing the rpm increases in the same gear for the same speed and therefore the powerband which you're in is more favorable, so if you compare 3000rpm to 3500 rpm you might be at 50 vs 60 HP output at wot (for the same speed) which is 10HP or 20% increase if you compare the 2, on the other hand with a t/b and airfilter your gains are more significant at over 4000 rpm since better volumetric efficiency is relevant at higher required airflow and piston speeds - and let's say you get 5% increase at max power output (6 HP for a 120HP engine), it's a lot less to evaluate when you're at a lower rpm trying to increase speed.
So even though the gearing won't gain you any HP it will provide more HP to the wheels at the same speed in the same gear, but it is more expensive and more involved than a simple t/b and airfilter + airbox mod.
