I enjoy pistol caliber carbines.
I have the Ruger PC-9 9mm, Marlin 45acp camp carbine, Marlin 1894 CP 16" 357mag/38spl, and the Beretta Cx4 in 9mm. The newest one I have had over 10 years.
The Marlin 1894 CP is the most fun, and useful. Accurate and reliable. Very light, and easy to use. This is the "Most Fun" rifle I own.
For Pistol caliber carbine matches and defense I would go with the Beretta first, and the Marlin 1894 a close second for defense. Primary reason is I have a Aimpoint H1 Micro Reddot turned on 24/7 and white light on the Beretta, which makes it much better for low light engagements. I don't want to mess with the aesthetics of the Marlin.
The trigger in the Ruger sucks and cannot in any practical way be improved, and the Marlin has never been reliable.
If I could only have one I would go with the Marlin 1894. Second is the Beretta in 9mm. For the semi auto's in semi auto pistol calibers, there is no real advantage of 40 or 45 over the 9mm. I am not getting any deeper into the caliber wars than that. My own opinion, based on my own combat experience and knowledge. Outside the house, I want a rifle caliber carbine, 7.62 NATO or if necessary 5.56 NATO.
I used a Thompson sub-Machine gun in 45acp of course, and a Swedish-K in 9mm in Vietnam each a few times. I much preferred the K over the Thompson by a good margin. I don't recommend pistol caliber anything for combat if it can be avoided, includes handguns too.
For high round count shooting I like the Beretta, I have factory magazines in 10, 15, 20, & 30 rounders. Meg-Gar offers 17, 18, and a different 20 rounders all of them very reliable. (Please note my carbine is set up for the 92 Magazines. So all these magazines will work with 6 of my Beretta 92 variants.
If a 45acp carbine is the ticket, I would go most likely with the Beretta, or maybe the HK with the 10 round only magazine.
Go figure.
Fred