These are my 3 absolute fave oracles but it's hard to recommend to someone else because you don't know their tastes and loves....
Earth Magic Oracle is a great oracle and has lots of positive reviews on AT. It's theming is really magical elements and the pagan year but doesn't go deeply into it, I guess it's "natural elements" as a theme. It's such a good general reading deck. I did a thread a few years ago on AT and read for so many people with this deck doing a 3 card reading for each. Each reading turned out so well every time, it's my most reliable deck
The publisher Hay House does a lot of oracle decks and I feel some can become a bit like "fluff", Earth Magic is by Steven Farmer who has done many for them, there is also many for them by Colette Baron-Reid (avoid her included little oracle books, they tend to be unhelpful if you read intuitively) and Doreen Virtue's Angel Decks. Obviously it depends on your own taste but I would be careful with the Hay House oracles, I've found them mostly disappointing. But the Earth Magic Oracle is stand out in the field. They are wildly available as a mass market deck.
Psycards - Barleywine mentioned them and I love them. They are based on Jung archetypes but have oracle images (I would say the theme is like medieval). They are a must have if you have psychological or analytical interests. They are also great for work and functional type readings. You have to get them from the webstore from the official site in your own country, so it's not mass market. They are made and created here in London and first published in 1982.
A'ha Oracle - Forum Member Linnie created this based on images that came to her in dreams. It's a marvellous intuitive deck and my fave for spiritual readings. They are mandala circles and the majority are only black and white, but a few are beautifully in colour. She felt she wanted to make the different colours and it really works when you don't think it should. Each card has a number at the bottom and you can look it up in the book but it has no keywords or anything and so you can read them intuitively with no prompts on the card! They always give you an indepth reading, you can't get a quick reading form them, it's just impossible
You get them from her own site in Oz and they are not massmarket.
In my Oracles collection, they are my 3 absolute favourites.