ExxonMobil (NYSE:XOM) and Royal Dutch Shell (NYSE:RDS-A) are two titans of the oil and gas world, but both are currently struggling to grow.

Indeed, on one hand Shell is selling underperforming assets around the world in an attempt to improve returns and drive profits.

Meanwhile, on the other hand, Exxon is struggling to replace falling production from its mature fields and, despite billions in capital expenditure, the company's oil output is only expected to expand around 3% between now and 2017.

But these two giants still have many attractive qualities, including their defensive nature, stable dividend payouts and clean balance sheets. So, which one is the better investment?

Struggling to replace falling production
As the largest oil and gas company in the world, Exxon's production is unrivaled. However, the company is struggling to replace falling production from its mature fields, and this is starting to hold back growth.

Exxon has more projects coming on stream during 2014 than in any other year in its history. Yet, these projects are only going to offset declining production from mature fields.

As a result, from now until 2017 Exxon's production is only expected to expand 3%.

It would appear that Exxon is going for production stability rather than growth, and is cutting capital spending during the next few years. Exxon spent $42.5 billion on capital projects last year; this figure is expected to fall to around $40 billion this year, and then average $37 billion during 2015 through to 2017.

Restructuring for a better return
Shell, meanwhile, is not chasing growth. Instead, the Anglo-Dutch company is trying to prune its portfolio of assets, targeting wider profit margins and better performance from current investments.

Shell has committed itself to $15 billion of asset disposals during the next few years, and is also working on rebuilding its North American business, which is currently losing money. Shell has invested more than $80 billion in North American projects, nearly 30% of the company's total asset base.

To try to combat this loss, Shell has cut jobs and packaged its North American business into a stand-alone entity, similar to the strategy BP has taken in North America. As well as the reorganization and job cuts, Shell is reducing its capital spending within the region. The company cut North American capex 50% last year and is planning a further 20% cut in capex this year .

However, Shell is not just rethinking its North American strategy -- it's tidying up its global portfolio, as well.

Earlier this year, Shell sold its refining and petrol station network within Australia along with other downstream assets including refineries within the UK, Germany, France, Norway, the Czech Republic, Egypt, Spain, Greece, Finland, and Sweden. What's more, Shell is looking to sell upstream assets in Nigeria, and has cancelled Arctic drilling plans.

The income question
With both Exxon and Shell targeting stability more than growth for the next few years, which would be the better investment for income seekers?

Well, at present, Shell's shares offer the better dividend yield, which currently sits around 4.6%, compared to Exxon's 2.6%. However, Exxon is also buying back stock, while Shell is not.

Breaking it all down, Exxon returned $27 billion to investors via both buybacks and dividends during 2013. On a per-share basis, this works out to around $6.10 per share, equivalent to a yield of 6.3%. As already covered above, Shell's dividend yield currently sits at 4.6%, significantly below the equivalent yield offered by Exxon.

If you're looking for growth
Exxon and Shell are two stable giants, and investing with them is likely to yield stable and predictable returns. If you're looking for growth, ConocoPhillips (NYSE:COP) could be the answer.

Conoco is targeting double-digit annual shareholder returns through both production growth, margin growth, and dividend growth. Specifically, Conoco aims to consistently deliver 3% to 5% compound annual production growth, while offering a compelling dividend from a diversified, high-quality portfolio of production assets.

That being said, Conoco is smaller than Exxon and Shell, so the company is inherently more risky as an investment. 

Foolish summary
Overall, it would appear that, for investors who are seeking income and growth, Exxon is the better choice over Shell.

Shell is not in growth mode, and the company is heading into a period of restructuring, which will not lead to output growth. Exxon, on the other hand, is targeting growth, albeit minimal. Still, Exxon's shareholder returns are much more attractive than those on offer by Shell, and these returns make the company look appealing as an investment.

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Rupert Hargreaves has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.