I guess the question then becomes, what is 'early Intel'? I think you can separate the Intel Macs into two eras - the first era with 32-bit, Carbon, etc, and the second era with 64-bit, Cocoa-only, etc.
It depends.
If you only care about the maximum compatibility for apps (Rosetta PPC + 32bit apps + Carbon) with the maximum power, you only need a Mac running 10.6, and that leaves you with a lot of subjectively good options.
You could get a bunch of 2011 Macs, with core i5/i7 that will do the job just fine.
But I'd not call those Macs "early Intels". 2011 was 5 years into the transition.
Apple in 2011 was an entirely different company compared to 2006, in the meantime iPhone happened, iPad happened, Multitouch gestures happened, whole different world.
If you're getting an early Intel, you're also doing it for nostalgia purposes, and that also means experiencing the way OSX changed from 10.4 to, say, 10.7. Which was RADICAL in my opinion.
With a 2007 iMac you can create eight partitions for 10.4 - 10.11 and experience all of this without any hacking, or even all the way to Ventura if you do.
Want some Aqua? Got you served.
Exposé? Check. Mission Control? Just reboot.
Multitouch gestures? Just pair the trackpad.
Transition from skeumorphic design to flat? We can do that.
And now I'm getting an itch to get one
Excellent for nostalgia purposes. Is a 2011 more mature? Of course it is. But if you wanted that you'd just get a new system