When space permits I prefer full-size 1U systems that have dual/hotswap power supplies and room for three low profile pci-e slots, such as a Dell R630/R640 or similar. With Intel chipset 4-port 10GbE SFP+ NICs this would max out at twelve ports plus whatever is on the motherboard daughtercard for network interfaces (2 x 10GbE + 2 x 1GbE copper, or whatever).

for smaller or shallow stuff, supermicro, msi, tyan, asus