When looking at reviews for Akai Professional, it's important to remember that Akai Professional, part of InMusic group, is not Akai, a brand which is applied to all sorts of electronics such as cheap TVs and cooking appliances. If there's a review for a TV here, it's the wrong Akai.
I bought an Akai MPC Key 37 and have discovered the MPC system for the first time - only 35 years too late, perhaps. This is a synthesizer keyboard based on the new MPC environment, so it's essentially a computer and software in a handy package rather than a traditional synth or sampler, but it works well, its fast, and has an amazing selection of presets.
I needed to contact Akai Professional support over the bundled software and online store partnership – they took a while to respond, but were very helpful once I had a customer service advisor to talk to (Monika).
The older packages and bundles are still tied to a partnership with FastSpring, which is a third party store and it has lots of issues with checkout and payment (even when buying a free item), it also charges extra for 'continued access to downloads' when Akai Professional offers continued access once you have bought something.
I resolved the issue with FastSpring not taking payment by filling out total nonsense in their checkout form - the only thing to remember is to make sure the email address used is the same as your InMusic profile.
If you've bought an MPC Key 37 which comes with a voucher for one free extra instrument, do NOT use it to get the MPC Stems expansion (that is only £9,99 and if you hesitate on checkout you'll get a 10% off code, so £8.99. InMusic should just make it a part of the MPC Desktop and Standalone package rather than trying to gouge such a trivial extra amount for it).
Akai Professional's MPC store has moved to a new checkout partner and I'm sure their future offerings will be more robust and user-friendly, harmonised across all InMusic brands. However, there's a worrying trend to subscriptions and DLC across all these types of instrument, and the MPC/Air subscriptions do not (as far as I can tell) extend to standalone MPC instruments, so check carefully before being tempted.
Jura and op-X4 are well worth having. My objection was that the free plugin did not include the option of getting the excellent "Fabric" one, which would make the MPC Key 37 very versatile.
Note that while marketing claims the MPC Key 61 has many more bundled instruments, the actual difference between the sounds provided with the 61 and the 37 is just six virtual instruments. The rest of the package is the inclusion of VST versions of the AIR softsynths, and some effects plugins.
These do have a high price normally, but Akai frequently offers promotions for MPC instruments and software, so don't buy them unless you NEED the sounds right now, or have waited for a discount.
The MPC Key 37 itself is a brilliant bit of kit, really versatile and flexible. After buying it I weighed up all the gear I owned and sold six things that it overlapped in sounds and process, worth twice what the MPC Key 37 cost even though they were secondhand. That illustrates what kind of value it offers I think... but I do hope they upograde it to 4GB RAM to match the 61 key, and it's a shame it doesn't have an M2/nVME slot as an evolution of the SSD in the Key 61 - instead, you add storage on an SD card which is certainly cheap and apparently not much slower than the Key 61's SSD interface anyway. The Key 37's exposed SD card feels more vulnerable than an internal nVME card would however, and since it holds your samples and projects, you'd want to make backups and protect it from theft at gigs.