I personally haven't tried any zooms with my m43 kit, only primes. Ones I had at one point or another - Oly 17 1.8, Panasonic Leica 25 1.4, Oly 45 1.8, Samyang 12 f2, Samyang 85 1.4, a combo of LensTurbo II & Samyang 10 2.8, and same vintage lenses I have in my sig (kept all of those). 45 1.8 is a gem of a lens, cheap, very small and light, perfect for portraiture. I ended up selling 17 1.8 for PL 25 1.4, but it was an awesome lens too, very nicely built (full metal) and plenty fast for street at night. PL 25 1.4 is a great fifty, nice and fast (although I've seen people complain that it's too big for m43, it was fine for my EM1, but I guess if kit size is a priority I'd go for another fifty). Samyang 12 f2 is so damn sharp and nice, it's an incredible wide lens, sharp across the frame wide open, by 5.6 it's too sharp
I really wanted to try pro zooms, but ended up switching systems, so haven't had the chance.