West Coast will come good soon enough. Huge supporter base, the bigger of just two clubs in the western half of the country (and this is 100% Aussie Rules territory- Qld and NSW are the rugby states). They've been strong for almost all of their 37 year existence, and teams go through cycles like they do in US sport due to draft and no relegation. In fact, if you perform poorly enough for long enough - and favoured by the establishment - they'll give you extra draft picks to boost your recovery. So getting in on a side on the ground floor is not a bad idea.
GWS is very exciting right now and are a "special interest" project of the AFL, so they'll never be allowed to fail. But they have very little following because Sydney Swans captured the local market 40 years ago. So you'd be getting a bit of Man City plasticity, minus cheating.
St Kilda are a perennial failureclub with one title in 127 years (remember: no relegation! And the league started with 8 teams, and still only had 12 teams in the 1980s). Nothing wrong with underdog sympathy, but be warned.
Collingwood, Carlton, Essendon and Richmond are the traditional powerhouses. Collingwood are never down for long, they seem to be Born to Runner-up but they have won enough flags (titles) to join Carlton and Essendon at the top of the pile (16 each). Richmond recently won three in a row but they're on the downward edge now so you'd be waiting a while for more good times. Carlton are looking good again after 20 horrible years. Last title in 1995 - as a Liverpool and Carlton fan I feel the parallels. Essendon have been mediocre-to-shit for over a decade now. If you choose them you'll be mocked as a drug cheat... mostly by me.
Geelong have been very well run for a long time, and benefit from being 1 hour from Melbourne and being the only Victorian club with exclusive use of its own stadium. You fucking suck if you choose Geelong, but if smug self satisfaction is your thing, go right ahead.
Adelaide clubs are worth consideration. Both have fanatical local support. Port Adelaide is more authentic, being derived from a historic club, the Crows are more of a modern creation, but the local rivalry is real and both clubs are usually competitive if not often premiership contenders.
Brisbane and Sydney are both strong clubs doing well in rugby territory, and won't be allowed to fail if they ever stop being well run. Do not bother with Gold Coast, they never got going and most people who don't work at AFL headquarters wonder why they even exist.
Hawthorn are usually very strong, currently shit. Long may it last (it probably won't). Melbourne, Western Bulldogs... eh. North Melbourne were always a nothing club to me, but the AFL are giving them extraordinary levels of draft assistance so I guess someone believes in them. Many thought they would relocate to Tasmania.
Speaking of which, Tasmania will have a club soon. I expect they will be right up there in a decade.
Oh, and Fremantle is the other team in Western Australia.