The Netgear ProSafe GS724TS is the closest competitor I've seen to the D-Link xStack DGS-3627 . Its port count and network throughput are similar to those of the D-Link DGS-3627, though it trails a bit on features.
Excellent price; 20-GigE proprietary stacking backbone; Good support for VoIP, video traffic
Dearth of advanced features (including PoE, higher-end security, Ipv6); Can stack only six switches (288-port total)