Originally posted by biz-engineer A1 or Z9 plus 3 lenses doesn't cost more than a Pentax K1 with 9 lenses, cover the same focal length range and the imaging performance is a level higher both in resolution, speed and video specs. Of course 9 lenses cover more than 3 lenses , but not so much more actually, because there is some redundancy. What is better, better body with less lenses, or lesser body with more lenses, that's the question everyone can answer for himself.
I'm going to ask you to show your calculations... because it depends on the specific 9 vs. the specific 3. Let's take a stroll down this path with my own calculations:
A1 $6500
GM 16-35 $2200
GM 24-70 $2200 (currently on sale for $2000)
GM 70-200 II $2800
Total: $13700 plus tax etc.
K1 $2250 (on sale currently for $1800)
D FA 15-30 $1450 (on sale currently for $1350)
D FA 24-70 $1300 (on sale for 1200)
D FA* 70-200 $1800 (on sale for 1700)
Total: $6800
You can swap around things a bit; for example if you toss in the Sony 100-400 (2500) vs. Pentax DFA 150-450 ($2000) you save another $500 (but probably need the 1.4x teleconverter on the Sony side pushing it to another $550 spent. However it is hard to get an a/b comparison where the ratio of numbers doesn't end up similar to what I am showing - nearly 2x cost for Sony - most of which is due to the A1! Sure you can add more on the Pentax side and the same can be true on the Sony side. Only you (currently) know what kit you would be comparing with.
For me - the K-1 was not an option I liked. The bulk of the camera plus the bulk of the 24-70 was more than I thought I would enjoy. The 28-105 probably would have sold me but I didn't have a place to try it. The bulk of the lenses for FF can be an issue with both systems although you can cherry pick smaller slower lenses and make that less of an issue easier with the Sony given the wider range of options in autofocus lenses. That's not an advantage per say - unless that's the way you prefer to shoot.
As someone who has used Pentax, Olympus, Samsung, Panasonic, and Sony I can say that in my experience the Panasonic (m43 gear only) was my 2nd favorite from a menu and function perspective. It was the easiest to navigate after Pentax. Sony is next and then Olympus. Olympus will always be last... lol. Samsung NX mirrorless was OK but it's been so long since I used it I'm not sure where to rank it. I feel like it was better than Sony, worse than Panasonic in terms of ease of use.
If it were me I would reach out to Chris Rankin (@lerolls) to ask him about his cross brand experiences. He recently sold off his K-1 gear but he has extensive experience with using Pentax and Sony, Panasonic, Sigma and Fuji. In the end I think Panasonic L alliance is his main go to system. I'm sure he can offer some perspective about switching that might be useful.
Here's my honest assessment: Any current gear from Sony, Nikon, Canon, Panasonic, Pentax, and Fuji can get the job done. Heck even OM/Olympus can do 90% of it. You would be hard pressed to fail to find a way to make good images with any gear if you have any skill and talent. So use whatever makes you happy and don't obsess. I suggest if you think Sony is the way forward you get a Novaflex adapter and a cheaper body and try manual focus or see if a large number of your lenses are compatible with the LA-KE1 Monster Adapter for K on FE. This will allow you a certain amount of testing and you can decide if you like the system enough to invest in it. Rental is another route you can explore. I really didn't think I would end up with much Sony gear when I got the A7RII - but monster's delayed release drove me to get a few lenses. My collection is very modest and I hope that the LA-KE1 will allow me to keep it that way without hampering my ability to use the system. I'm lucky - I have the $ to dabble and I have a father to share my interests. I am not able to run out and buy whatever I want - so no A1's in my stable with multiple GM lenses... but that doesn't stop me from enjoying all my gear.
---------- Post added 02-01-22 at 01:29 PM ----------
NOTE that switching to the A7RIVa as the body of choice means dropping to $3500 vs. $6500 which makes the total $10700 not $13700 which is pretty significant but still nearly 60% more than the Pentax system. Only you can decide if 2x or 1.6x is worth the difference in cost for the potential benefits you see. Those cost numbers are not indicative of the costs on a lens only basis. The lenses seem to vary a lot. Many are only a 25% premium over Pentax until you get into the large primes... then things soar.