Hey dude - your initial experience sounds similar to mine - read below to see why I say YES YES YES to a Mac Pro tower 'upgrade project'
I started out buying pre-packaged Macs too (in the glory years between 2010 and 2013 I reckon I owned 3 macbook airs, 5 macbook pros and 3 iMacs) and that was because they had gotten so far ahead of windows on hardware innovation that I had to set aside my long-standing and profound dislike for the Mac operating system and give Apple another chance to win me over. They smashed it out of the park with things like exceptional build quality, thunderbolt and retina displays. It was all just a game changer in my mind and I've been a mac user ever since..
The preamble is only relevant because I encountered an issue (bug actually) with Mac and thunderbolt that interrupted my workflow so badly that I thought my only choice was to go back to Windows.
Then I discovered the Mac Pro tower (or "cMP 5,1" as it's generally referred to on this forum) and realised I could have it all.
It's been the BEST 'upgrade project' I have ever had the good fortune to stumble upon. A little research at the outset revealed possibilities that I simply didn't know were possible. I could own a Mac with 96GB of RAM!! and 24 CPU cores!! This meant I could run three virtual machines in the background of macOS and still have more power in OSX and in each of the individual Windows Virtual Machines than I had ever had in the most expensive Windows workstation I had ever purchased in the past.
Then I discovered NO thunderbolt means NO system crashes during massive data transfers of critical information. No more time wasted on data recovery OR investigation of what was lost when thunderbolt raid configurations compulsively started dropping out at say 420GB in to a 650GB file transfer.
Then it got EVEN BETTER.. after I bought one I discovered this insanely beautiful and well engineered Mac Pro tower had these things called "PCIe Slots" which would let me do my massive file transfers 2.2x FASTER than thunderbolt.
Then the 'upgrade project' obsession mode really kicked in HARD. Transferring datasets at 2.2x thunderbolt was more than I needed or hoped for - but I noticed hardware upgrades for the The Mac Pro tower PCIe slots that might let me clock transfer speeds of 4500Mbps. So I did it (HIGHPOINT Rocket Raid 2744 with PCIe 2.0 x16 link speed).. but STILL I wanted MORE and then I discovered (almost by accident) that the graphics card (GPU) required for display output was occupying SLOT 1 by *convention NOT by necessity* ..so - firmly in the grip of my speed addiction - I shifted the GPU to SLOT 4 so I could use the x16 link speed in SLOT 1 to see if I could double the transfer speeds again or maybe just get the Mbps number up above 7000 and guess what.. by installing more upgrades (like my Highpoint SSD7101 NVMe host controller) - YOU CAN!!
In short - it's the most fun and flexible upgrade project you'll ever undertake. At the same time - I have to warn you that it can get expensive. Passion for the hobby/project and all the knowledge that falls out of the bottom of hundreds of hours of research and hundreds more in trial and error (before I discovered this forum) is rewarding for some and crazy in the eyes of many others.
At this stage, I have worked out how I can get to maybe 9 or 10 Gbps but realistically, I've managed to get to record breaking levels for a bit over USD $4000 and the hardware changes/upgrades I would need to make to get the extra 2 - 3 Gbps would conservatively cost another USD $2500. So I can't afford to feed the obsession to the point of fiscal negligence. But I probably will..... I'd rather mod a Mac to within an inch of it's capability ceiling than build a new PC out of the recycled plastic rubbish from vendors that invest millions ($) on the 'manufacturing and production' phase and less than 3 days and $45 on the 'engineering and design' phase. Maybe they went $10 over budget when they came up with RGB lighting strips but I doubt it.
