Well, I’d have to say “much” more enjoyable is up for debate, and the places my wife drives the 100, a locker is far handier. She’s used the center and rear lockers to get unstuck when playing solo more than once.
Again, another subjective point. I’m very satisfied with the ratios in the A343. The money I didn’t spend to buy a 5 speed truck (which all seem to be priced substantially higher in my area) allows my wallet to be much more efficient!
There is no right or wrong answer here. Any 100 series is great out of the box, and has the potential to be downright amazing with very few mods.
From a subjective standpoint:
I've owned a 98 LX, my son's DD is a 00 LC, and my DD is an 06 LX. I've owned (1) A442F, (2) A343F and (3) A750F equipped Toyota vehicles. My son’s (4spd) LC, it’s still a huge improvement over an 80 series, and I wouldn’t sell a perfectly good 4spd 100, just to get an extra gear. If I were in the situation that I didn't already have a 100 series, I'd strongly lean towards the 5spd. Yes, they are all good, you have some minor trade-offs between the different model years of the 100 series, and there is no right or wrong answer.
From an objective viewpoint:
In 1st gear, an A750F and a 4.1 axle is roughly equivalent of a “5.15” axle ratio in an A343 equipped vehicle. While at the the same time, in 5th gear, the A750F and a 4.1 axle, is the equivalent of a “3.92” axle in an A343 equipped vehicle (in 4th). So you get the benefits of an axle gear swap (or a Mark’s 3:1 TC gear) without the drawbacks.
As a wife/kid daily driver, Lockers vs. Letters:
So your wife has actually used the OEM locker buttons. If I’m putting a wife or kid in a tall, top heavy vehicle that’s main usage is on the road, it is my viewpoint is that having VSC, to keep it on the road under wet/icy road conditions, might be more important to me than a locker. While ATRAC might be less efficient than lockers, a Harrop or ARB locker is a whole lot easier to install than it would be to retrofit “letters” onto a 98/99 100 series
As for wallet efficiency:
I probably didn't do so well there by buying new, then again I've been driving the same DD for the last 12 years, and expect to drive it for many more.