I'd buy a MKIII or MKIV for the push-button magazine release, but not for the simplified take down. As a matter of fact, I did. At one time I had 4 MKIIIs. On the MKIII, the loaded chamber indicator can be easily removed, left out, or replaced with a solid metal "filler," and the mag disconnect can also easily be removed.
My favorite Ruger MK pistol was a 6 7/8" stainless, tapered barrel, Target MKII Target that I shouldn't have sold soon after buying a MKIII. It looked and balanced even better than my 6 7/8" MKIII Hunter or 6 7/8" MKIII Target, but I prefer the push-button mag release, am biased towards stainless steel, and a tapered, long barreled, MKIII target was never offered.
My current favorite MK is a MKIII stainless Hunter with a 4.5" factory barrel and VQ trigger and sear. If I were to buy one now, it would be a MKIV stainless model of sorts with the stainless steel frame; probably the bull barreled Target, or the slap-sided barrel Competition, since they haven't reintroduced a tapered barrel Target model.
If you have the discretionary income, just buy what you want. Life's too short to skimp on something so small that can make you happier. If you find you're no longer shooting, or admiring, the model you currently own, sell it, but only after you have the next one in hand.
Cheers