From the logs it looks like the SRX does not receive replies to the IKE requests but the SSG is responding.
I think this might be because of the zone configuration on the SRX. You have IKE allowed at the zone level but you have specific services on the interface that does NOT include IKE. Please add IKE to the interface here.
security-zone Internet {
host-inbound-traffic {
system-services {
ike;
}
}
interfaces {
fe-0/0/0.0 {
host-inbound-traffic {
system-services {
https;
ssh;
}
}
}
}
}