I chose the 400mm length 4U, steel covers with 10mm front plate. Having spent hours on AliExpress I have found comparable ones but the problem was always with the shipping cost ; some nearly $200 which is insane. On the other hand, shipping from Italy to New Zealand for $40 is a very competitive price and would arrive much faster than China Post. Another point to add for those living in NZ, recent changes in GST / Duty have allowed items to come into NZ duty and tax free for amounts under $1,000 NZD providing the seller does not do more than $60K of annual sales to NZ residents (for which they do not have to be GST registered ; a great savings for NZ online shoppers at diyaudiostore.com). This is different to purchases on eBay & AliExpress where they pretty much blanket all sellers to charge the 15% GST for items shipped to NZ. Previous rules was anything over $330 NZD would require customs / duty processing.
This chassis will serve for my CSX1 VFet project (using permanedre's PCBs). I went with the 4U height which would allow me about 90mm of working height (depending on how wide the angle heatsink brackets are). This working height space was critical to partially fit the transformers under the PCB that lays horizontal. Choosing the baseplate option would get you less vertical space.
Assembly of the chassis is pretty quick and as others have mentioned, always have the screws in the support rails fit loosely so you can close up any gaps before tightening. The chassis comes with plastic round feet, for which I probably spent more time fitting them to the bottom cover. Note the bottom cover has no pre-drilled holes for the feet screws so be careful drilling if you want them to line up with the existing holes in the support rails.
I'm not a fan of having the heatsinks in 2 pieces per side as this reduces efficiency of heat dissipation. For eg. a layout where more transistors were mounted on one heatsink than the other could pose a problem. I recommend going with the 10mm thick front plate as there are only 4 screws that mount it, via on ends of the support rails, to the rest of the chassis. With a thicker front plate, you allow more screw threads into the plate for more strength. I did not choose the front handles option as they were mounted for looks and prefer a single handle mounted horizontal in both front and back plates. The rear steel plate appears to be strong enough to suit the same horizontal handle as the front. I do like the extra 'tapered head' screws which I will use for a clear plexiglass top cover.