Both Good
Both Good
The M2 is a classic Leica built during the time many consider to be the high point of craftsmanship. It has a simple and elegant viewfinder, slower loading and rewinding. It was actually considered as a cheaper version of the M3 but became more popular due to the 35mm frameline in the viewfinder.
M4-2 was Leica's attempt to starve off bankruptcy after the disaster of the M5. Some will say it was more cheaply made in Canada and lacks the craftsmanship of earlier cameras. It looses the self timer from the original M4 but gains a motor winder option. As with the M4 over the M2, the viewfinder has a 135 frameline, faster loading and the tilted rewind knob.
Personally, it comes down to feel. Both cameras would serve equally well and if the price is the same, get the one which you like the best. I use an M4 and would add either as a second body (would lean toward the M2 because I love its viewfinder).