As Snags indicates, your budget is an important factor. For example, if price is no limit, you'd find it hard to beat the Shure SE530 (which seems to be universally well-reviewed):
http://www.amazon.co....-Bronze/dp/B000POI5N0
For £40 still stick with Sennheiser but look further down their range. It also depends what you've currently been listening with: if you've been using those sh1tty white things from Apple then Sennnheiser's CX300 IIs will be a great improvement.
homedeeth. You can get the CX300 IIs cheaper than that Amazon price on ebay. Just make sure you buy genuine as there are many clone/Chinese versions floating about.