just BM-21
Azerbaijan bought a new batch of Smerches but Kasirga has a much bigger range I believe almost double
as it is a more advanced version than the ones Turkey uses
Indeed, Azerbaijan gets newer and better Kasirga T-300's than even what the Turkish Army currently has - see Jane's report on that: janes.com/article/12882/roketsan-offers-new-mrl-system
However, it's highly doubtful that T-300 Kasirga are better than or even equal to Smerch-M BM-30. For starters, SMERCH-M has about 22 different rockets that could be chosen (e.g., 9M55K - Cluster munition, anti-personnel; 9M55K1 - Cluster munition, self guided anti-tank; 9M55K4 - Cluster munition, AT minelets; 9M55K5 - HEAT/HE-Fragmentation; 9M55F - separable HE-Fragmentation; 9M55C - Thermobaric; 9M528 - HE-Fragmentation, 9М534 - with a UAV, and many more), vs. Kasirga that seems to have only one or two.
Secondly, the SMERCH's that Azerbaijan has (which are SMERCH-M with a range of up to 90 km, thus improved on classical SMERCH which has a range of 70 km. Keep in mind that the new SMERCH [3rd generation] that Russia started to recently export carry only 6 rockets, thus reducing the weight by 50% and making them acceptable for European and other customers who care about their roads that can't take nearly 47 tons of weight) can carry and fire up to 12 rockets at once vs. only 4 by Kasirga.
That means Azerbaijan needs to have more drivers/crew during war, and attract more attention (e.g., Azerbaijan's 30 SMERCH systems can fire 360 rockets at once - to achieve the same equivalency from Kasirga it would require Azerbaijan to have 90 T-300's, with 90 drivers instead of 30). Do you think Armenians would have easier time to spot 90 vehicles or 30 vehicles moving closer to the frontline? More importantly, with all the other MLRS/rocket/missiles systems, tanks, APCs and artillery, Azerbaijan would need an ARMY of drivers in addition to an army of soldiers-fighters. That's definitely not a good situation.
Thirdly, we know little about the precision of the new Kasirga, which is untested and never been used in any wars. Here's its official page: roketsan.com.tr/en/urunler-hizmetler/kara-sistemleri/satihtan-satiha-roket-sistemleri/t-300-cnra-300-mm-cok-namlulu-roketatar/
I would be very surprised if Armenians have not yet learned how to at least try to disrupt GPS in the war theater (Kasirga uses GPS). Russians might have supplied them such technology (e.g., system AVTOBAZA). Not to mention that GPS can't be very precise in forested, mountainous area (neither can laser, or thermal, but a combination is needed to improve accuracy). But we do know that SMERCH is very precise, which is exactly what makes it so lethal and so awesome.
Smerch is very precise - at 70 km., it has a circular error probability (radius of error) of just 0.21% or 150 meters. The old Kasirga T-300 had a CEP (Circular Error Probable) of ~1% of range - which at 100km would mean 1,000 meters or one kilometer! This is the Achilles heel of all these MLRS systems that are SMERCH wanna-be's: they increase the range and do all kinds of other modifications, but their accuracy rarely equals, yet alone surpasses, that of SMERCH.
Fourth, keep in mind that Kasirga is a Turkish version, improved and all, of the Chinese WS-1B - which in itself was a Chinese reverse-engineering (rip-off) of Soviet SMERCH. Thus, despite being designed in the 1980s, both Turkey and China are still trying to equal SMERCH.
Finally, keep in mind that just one SMERCH with 12 standard 9M55K Cluster munition/anti-personnel rockets covers 40 hectares of land (which is about 99 acres of land, or 400 dönüm's of land to make it easier to understand for Turkish forum members). That's over 672,000 sq. meters of land!
Just 3 SMERCH systems with 12 rockets each are equivalent in their effectiveness to 2 brigades of 9K79 TOCHKA-U (which both Armenia and Azerbaijan possess). As a note, in the Soviet army, one rocket brigade had either 2 or 3 divisions, and each division could have 2 to 3 battery's with 2 to 3 TOCHKA-U's. Thus, each Soviet brigade could have anywhere from 12 to 18 TOCHKA-U, and thus 3 SMERCH systems are as lethal as 24 to 36 TOCHKA-U's (although SMERCH's range is a maximum of 90km, whilst TOCHKA-U is 120km, but one SMERCH's rocket - 9М542 - has increased its range to 120km).
Thus, while the latest modification of Kasirga might indeed be more lethal, more accurate, and longer-range than older Kasirga or older (first generation) SMERCH - let's hope so for Azerbaijan's sake - it would still be just 4 rockets vs. 12 in SMERCH. And it's doubtful that the new Kasirga could improve its accuracy to 0,21% CEP, or get a whopping 22 types of missiles to chose from, although Turkey did implement GPS/INS guidance for latest Yildirim's and supposedly improved CEP to around 50 meters (although that needs to be verified).
In any case, Azerbaijan seems to need all the firepower it can get in order to liberate its lands, and even if Kasirga's (or Kasirga-G's) are not very accurate, they are still needed to aim at centers of Armenian army such as at their bases and fortified areas.