I've never owned a Herald, but we do currently have a Minor.
Yes, Minors are good, but to put some balance on the "spares" situation - spares are still pretty easy to get for Heralds, especially engine parts and other more common parts, so don't think that spares would be a major headache for this car. OK, so it's not as good as for a Minor, but vitually nothing is. And regarding Minor spares, my experience is that they are cheap and plentiful (so much so that you can reputedly build almost a whole car from spares should you so wish) but very often the quality of the spare parts is woeful - I've had quite a few parts that are so poor they are almost "not fit for purpose" so don't get too carried away with the "Minor spares are easy" thing.
The other thing is that for £1500, you will get a Minor that DEFINATELY needs work, fully functioning "needs nothing" Minors start at over double that, so bear this in mind too. I don't know much about Herald prices, but you might get a better Herald than a Minor for that money.
Overall then I'd say that there's not much in it - Minors are VERY common, so the herald will be a slightly more interesting car to own, and probably slightly less "old fashioned" to drive - depending on what you want this could be a good thing or a bad thing. Certainly the comments above about one being a chassis car and the other a monocoque are valid, I know that working on the engine on a Herald is bliss, because access is so good, most of the time you can sit on the front wheel while you work! However, the minor was designed for a flat-four, so there's loads of room in that engine bay too.
Your call at the end of the day, I think you could be very happy with either car to be honest!
Here's our Minor, bought for £3.5k 5 years ago:

Cheers
