As the end of the tax year draws to a close it brings into sharp focus the use-it-or-lose-it aspect of the annual ISA limit. Indeed, ISA providers from banks and building societies through to the likes of Hargreaves Lansdown and AJ Bell are encouraging savers and investors alike to make the full use of their £15,240 ISA allowance.

In my view, where possible, both investors and savers should take them up on their offer and save as much cash as they can afford, after all once the tax year ends the allowance is gone forever.

But what to buy – cash, bonds or shares?

Despite my view that over a long period of time investing in shares will always beat cash and bonds, I would never advise anyone to be 100% in any asset class.

Indeed, you should always hold enough cash to ensure that you can sleep soundly at night, not to mention being able to cover the boiler breaking down a week before Christmas.

Bonds also have their place in a well-diversified portfolio. However, they can be more risky if you’re inexperienced in this field and it often pays to employ someone to invest on your behalf.

Which brings us nicely onto shares. And for those investors, whether experienced or otherwise, I can’t think of many other shares that you can buy and almost forget about than Unilever (LSE: ULVR)British American Tobacco (LSE: BATS) and Reckitt Benckiser (LSE: RB).

While there are no guarantees in life, and especially in investing, I think that anyone investing their cash into these companies, even at todays prices will see positive results in 10 years’ time. The key is to almost forget about the fact that you own shares in the company, leaving the business to compound your returns over a long period of time.

The 10-year chart says it all

Now, I would be the first to admit that it’s rather scary to buy into shares that are hitting new all-time highs. However, I can’t remember a time when any of these quality businesses were ‘cheap’, apart from maybe the low point of the 2008-09 financial crash.

However, even those who bought the shares at the height of the 2007-08 bull run would have still doubled their money – sadly the same can’t be said for the FTSE 100 over the same period.

In my view the reason for the outperformance is due to the fact that each of these businesses has a defendable moat – this is the type of company characteristic that Warren Buffett looks for in the companies that he invests in.

Still good value?

Taken as a basket, these shares trade on a forward PER of over 20 times forecast earnings and yield just over 3% according to data from Stockopedia – that’s more expensive than the FTSE 100 and with a slightly lower yield.

However, not all of the companies listed in the blue-chip index can boast a place in the top quartile when it comes to measures such as operating margin, return on equity (ROE) and return on capital employed (ROCE).

In my view, investors should look to put their hard-earned cash into businesses that can turn a profit whatever the weather.

And on that note, I'd like to take the opportunity to present this special free report. Within, you'll find five shares that have broad global exposure, and dominant market positions, as well as strong brands that should provide steady cash flows that long-term, disciplined investors look for.

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Dave Sullivan has no position in any shares mentioned. The Motley Fool UK owns shares of and has recommended Unilever. The Motley Fool UK has recommended Reckitt Benckiser. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors.