When I was looking at suburbs in Adelaide, I needed to make sure it has everything me and my family needed. Tea Tree Gully has all of that. Less than a thirty minute drive and you are in the city, close proximity to the hospital, Westfields shopping center and some of the best schools Adelaide has to offer. With an affordable median price, its a great place to begin your search.
Golden Grove if you don't care for stuffiness or toffs and don't mind a bit of a commute in or out of town but generally otherwise anything 8km minimum out of town is the way to go.
Belair, Hawthorndene, edenhills, blackwood etc. Inner south such as colonial light gardens but abit pricier than the hills. Try happy valley or aberfoyle park for a cheaper safe area. But the first suburbs I listed are safe clean and great for families and still relatively close to the city
Typically you will achieve higher resale values in the CBD and inner Eastern and Southern suburbs (these are our "blue chip" suburbs). Safety isn't directly related to value and as such there are many areas to consider. To achieve a nice balance of value and your 3 criteria I like the CBD itself. I am biased because I also live in the CBD, but I consider it undervalued from a professional point of view. It has undergone the most radical change recently (for the better - markets, nightlife, restaurants etc) and plans exist to improve it further. We are surrounded by parklands and the city squares provide plenty of greenery. The South East corner is the most expensive but provides lovely character cottages and brand new townhouses close to the lifestyle strip - Hutt St. The South West corner is cheaper but less affluent, while still providing great cafes and proximity to everything you could want. The Northen end of the city is mostly apartments and more of a genuine "CBD" in that it contains most of our office buildings and corporates etc.
I have lived in Salisbury for five years and feel very safe here.
It's very cosmopolitan and has great public transport and a lot of shopping areas. There are also public and private schools, good medical facilities and public and private hospital. Entertainment is also great with many cafes, take away, cinema, pools and parks.
It is centrally located, 35mins to the CBC (25mins on the train), 25mins to Gawler, 15mins to Golden Grove and Tee Tree Gully, 30mins to Norwood, 30mins to Semaphore Beach and 45mins to the Barossa Valley.
Good place for families on a budget and retirement as housing is very affordable.
The best places that fit your criteria would be:
Semaphore (amazing place with history, old homes and new, great jetty and main street with lots to offer. Would often visit the main street and go for long walks.
Colonel Light Gardens, Lower Mitcham & Mitcham. I have lived in Mitcham and Colonel Light Gardens and loved these places. Safe, good transport, great homes, and good facilities. The Edinburgh Hotel is great!
There are so many good suburbs in Adelaide for young people!
Check out this article on all of the best: https://www.switchliving.com.au/student-guide/go/adelaide/best-suburbs-adelaide/
Personally, I love the CBD and North Adelaide - and so cheap compared to Sydney prices!
Do be aware that the northern suburbs of Adelaide regrettably although rental and property prices are lower are not always very safe. I’m talking about the Elizabeth and Davoren Park areas although there are decent areas out there can vary from street to Street.
Due to the lower housing costs there are a lot of people with difficulties and therefore drug issues and crime is fairly high.
I think the advice of everybody else on this post is pretty sound. Good luck with it all.