I really like the iMac + iPad combo.
The iMac allows me to do everything I need for work plus the flexibility of a large, versatile display and great speakers for media and personal enjoyment. I can work and play in one simple, clean package.
The iPad is the true portable device, allowing me to do ‘just enough’ in terms of productivity so that when I get back to the iMac it’s only a small number of steps/tasks. iPad is also very convenient as a leisurely experience, of course. I can kick back on the couch and web surf or hold the iPad up to a client at work to demonstrate something easily.
I have nothing against MacBooks and think the current lineup is excellent, but really it comes down to weighing up how you’re going to use your devices rather than the cost. Everyone’s work experiences are going to be different enough that no one setup is going to be perfect for everyone, despite what influencers want you to believe on their clickbait videos.
I’m fortunate that I can get away with an iPad for work as I mainly live in MS Office and some reference apps that, conveniently, are cross platform with native Mac apps (ie Complete Anatomy), but it’s not this simple for everyone.
iMac is also excellent value compared to a MacBook + display combo, and there’s no risk of tiring your battery prematurely for having it plugged in long periods.
One caveat with the iPad; get used to typing on the display. I don’t buy into the idea of purchasing a ‘folio’ keyboard (which in the entry iPad’s case is literally a backside case plus a magnetic keyboard, with no front option for front protection other than the thick keyboard…) for half the cost of the device, as that defeats the whole concept of the iPad being slim, light, and more affordable - in this instance just get a MBA!
However I do highly recommend Apple Pencil for writing with. I was able to pick up the new USB-C version for £65 and it’s one of the best Apple purchases I’ve ever made, absolute game changer for making notes with clients whilst holding the iPad in ‘notepad’ fashion.