I go purely Vanguard Index Funds (specifically high-yield shares because their long-term return was higher than the regular share index at the time of choosing which to open), but I have no debt other than HECS.
Calculating whether to pay down your mortgage or invest is fairly straightforward once you understand the effect that tax has on your investments.
Paying down your mortgage gives you a return in after-tax dollars equal to the interest % of your loan. The return is in after-tax dollars because each dollar you need to pay in interest is an after-tax dollar. Say your interest rate is 5% (reasonable atm). If you pay off $100 of your loan, you are better off by $5 each year, permanently. But! That is an after-tax dollar. Someone in the 34% tax bracket (earning $37,000-$80,000 and including medicare levy) would need to earn $5/0.66 = $7.58 before tax in order to be $5 better off after tax.
Therefore, a person in the 34% tax bracket should consider repayment of a 5% loan as a risk-free 7.58% pre-tax return.
Can you get a return of better than 7.58% risk free - or are you willing to take a risk in order to get an extra return? If so, invest. If not, pay down debt.
For reference, Australian Real Estate Investment Trusts (REITs) returned 9% per year over the 20 years to 2011; shares returned 8.7%; bonds returned 7.6%. All pre-tax.
For a person in the 34% tax bracket, these would be equivalent to paying down a mortgage charging 5.94%, 5.74% and 5.02% respectively. So the best after-tax benefit our hypothetical 34% tax, 5% loan person could get by investing instead of paying down their loan is... 1%ish. That's $1 a year for every $100, and in return you have the risk of enjoying the next crash and needing to wait a long time to end up in front.
In other words, if you're paying 5% and in the 34% bracket, you just might consider investing instead of paying off the loan. Might.
If you're paying 5.5%, don't bother.
On this basis, I am very confident in advising* you that you should focus on paying off your home loan first. It frees you not only from the financial burden of needing regular cash but also the psychological burden of always needing to come up with cash every payment period.
However, I do recommend holding an emergency fund of some kind. How much do you need? I can't give you an exact figure. Factors include health (including immediate family), prospects of losing work / seasonality (and expected time to gain new employment if necessary), psychological need for reassurance, and many more (car ownership springs to mind). I don't have much in emergency fund because: I don't have children; my rental arrangement is very secure; I have good employment prospects; I am in good health; no car; I have rellies I could beg from if worse came to worst. Think about the worst thing that could happen to you, and try to sit down and figure out how much money you would need to be able to deal with it.
Generally the amount is based on some period of time and either income or expenses over that period of time. Some people like having 2 weeks' expenses, some 4 weeks', some even 3-6 months' income set aside. Mine is about 4 weeks' expenses. Decide on a figure that gives you reassurance - that's the most valuable part of the emergency fund, to me. If in doubt, hold more in reserve.
My preferred method would be to have an offset facility on the home loan, so you can redraw your extra repayments and they reduce your interest burden. If you don't already have one, it may be expensive to set one up; I'm not too familiar with this, though. Talk to your lender.
My next preferred option would be to hold a bare minimum, 1-2 weeks' income in a bank account and any extra in an index fund. There's a little extra hassle: Vanguard requires a mailed or faxed form, and generally send money in one week or so - but that timeframe is not guaranteed.
More cautious types would suggest keeping the whole amount in a regular bank account, or split across two bank accounts across two different banks, or even under-the-mattress. I don't see any reason why a regular bank account wouldn't suffice, but then I've never witnessed a bank run, either.
Dump every cent left over into your home loan and watch that sucker wither and die as it should. =)
Links:
Long-term return figures:
http://www.asx.com.au/documents/products/ASX_Report_2012.pdfHome loan rates:
http://www.canstar.com.au/home-loans/compare-home-loan-interest-rates/Appendix (because forum posts with appendices aren't pretentious in the slightest):
Mini-table of tax rates and effective returns for paying a debt:
Interest rate
Taxrate 3% 4% 5% 6% 7% 10%
0% 3% 4% 5% 6% 7% 10%
19% 3.70% 4.94% 6.17% 7.41% 8.64% 12.35%
34% 4.55% 6.06% 7.58% 9.09% 10.61% 15.15%
38.5% 4.88% 6.50% 8.13% 9.76% 11.38% 16.26%
Includes ML @ 1.5% for 32.5%+ brackets; does not include ML for 19% bracket; does not include ML-Surcharge. If you're earning enough to worry about ML-Surcharge or the 45% bracket, hire a professional, or wait a few years until I finish qualifying. =)
Also, this table should identify why anyone earning decent money in 'Straya should NOT have a credit card balance.
EDIT: forgot the *:
*Not a professional. Not professional advice. Magical fairy on an internet forum.