hello guys

so we got 3 offices

the HQ got 5 DSL lines with static ip
and we got office 2
and officer 3 both with fiber connection

i wannt to bridge the 3 offices over vpn and i wannt to know what the best knowing that we got a data serer in the network and we got Voip server Avaya so i connect them without any trubles or loss in the packets

wich is better

PPTP
L2P
Ip/ip
IP Sec ?