Azerbaijan has stated at the beginning of 2018, They would enhance a stronger defence cooperation with Russia because of Armenia's newly acquired weapons from them...
For their Army, Azerbaijan started to look at procuring the T-90MS, TOS-1As, more BMP-3s, Khrizantema-S Tank Destroyers and 2S19 Mstas. Azerbaijan expressed interest in procuring 50 BMD-4s to be used as light tanks and procuring 80-100 SPM-3 Medved armored vehicle... some sources even hinted around at the fact Azerbaijan is looking at previous deals and might send 100 T-72s to Russia to be converted to the BMPT-72 Heavy Infantry Fighting vehicle. There is also a possibility that Azerbaijan could be the launch customer for the Uragan-1M. There is also rumors indicating that Azerbaijan has interest in purchasing Krasukha-4 EW Systems, and purchasing the Kasta-2E Radar.
For their Air Force, Azerbaijan is now looking at possibly acquiring the SU-35 or MiG-35 due to the fact that Armenia is receiving SU-30SMs in the future, some say as many as 20-40 aircraft could be acquired, Azerbaijan appears to leaning more towards the SU-35, which means if you exclude Russia, Azerbaijan will have the strongest air force in the Caspian region. There was also mentions of Azerbaijan Mi-28NMs ~30-40 of them so they could move their Mi-24Gs to their border troops. They are also looking at buying 20 Yak-130 trainer jets.
For their Navy, Azerbaijan has expressed interest in procuring 3-5 Project 22160 Patrol Ships and 2-3 Improved Kilo Class Subs which would make them the strongest navy in the Caspian again excluding Russia. Azerbaijan is also looking at a deal from 2012-2013 in which they were to purchase 8 BAL Coastal Launchers for the defense of their coast line and oil refineries.
For their Air Defence forces, Azerbaijan was looking at having Russia install a manufacturing facility for the production of the Igla-S MANPAD. There has been reports of Azerbaijani officials holding negotiations of another S-300PMU2 battery as well as looking at the Sosna SAM to replace their ageing Strela-1/10 air defence systems. some unofficial reports claim Azerbaijan is looking at new Medium Range SAMs, in which Russia is ready to propose the S-350 "Vityaz" to them. They are also looking at procuring ~30-50 Pantsir-S1s to replace their ZSU-23-4 "Shilka" SPAAGs sometime.
as an additional note, I seen one source (I highly doubt tbh) anyhows claim that Baku could be potential as purchasing the S-400.... but lets see if that happens.