you need to tell us more and what your aim is
350 expensive to SFH and not common to find, but good for commercial work
206 always useful as there are a lot about to sfh
500 if you want to have fun, probably the cheapest in terms of cost v miles done
EC120 wouldn't bother with as very few about
480 not that many same performance as a 206
341 fun to fly but expensive as you can't hire an ex mil one
R66 no comment