There are some great lenses in that format. I'd recommend waiting until you know why you need more lenses before buying. Basically you want wider or narrower reach or you want to take in more light or some combination of both. These things will determine which lenses you need. My personal kit is the 14mm Panny, the 20mm Panny, and the 45mm Oly. All 3 are wonderful and do most of what I'd ever need.