For the multi purpose uses you mention, I reckon there are many a choice. A few I would recommend:
Garrett - Ace 250 and the GTP 1350
These have enough power to get things fairly deep and enough features to make a newbie fee like he has something. This instills confidence.
The downside of these is they can be quirky at first.
Fisher - One of the CZ models
These are very deep and have enough features, too. Like the Garretts, they are easy to use initially and offer headroom to grow into.
Whites - some of the older ID models like the IDX, Eagle, etc. They are smooth in operation and,again, offer ease of use - with enough features to make a newbie fell like he has something.
Tesoro - I hesitate to recommend any but the DeLeon or the Cortez. The other Tesoro units are nice, and I've owned a'many of them, but they are beep and dig detectors. Most newbs today expect some "electronics" for their money and the mentioned models have that, giving the newbie the sense that he has something...
A common thread here is the options available in the form of user features. Things like notch and digital displays and so on may not entice the jaded purist or hardcore relic head - but most newbies aren't in that groove. They dont know about kilohertz and ground minerals and halo effects... you know, all the minutae we long timers love to drool over. Instead, it's important to them have something for their money; to get value, as it were.
Some would say that a newbie should keep it simple and there is merit in that argument. But newbies often feel cheated when they go that route. SO let them get some features to keep them interested.
I also suggest they follow Charles Garrett's advice and decide on a price they can afford, add a hundred dollars to THAT figure - and then make a purchase. That way they get a capable machine with plenty of features and functionality, which also offers eomroom to grow.
I also agree that one should get used gear when starting out - for all the reasons already mentioned.
Finally, and this is for you: commit to stick by your friend as he develops.