While I would be inclined to use after market cartridges as they are much cheaper then originals, and printers are generally cheap relative to the costs of consumables, not all after market cartridges are equal and the quality is not always as good as the originals.
I believe that "Which" in the UK is a Consumer funded organization. This article talks about replacement ink cartriges, and has a useful table on the their users experiences. In summary, 63% of users had no problems, about 35% had problems related to print quality, 3% complained of ink spillage and 10% complained of other problems. (I have no idea why these figures add up to > 100% !!!). If you happen to be in the UK the article is also useful as to investigating your rights as a consumer.
A report (requires subscription) on printer reliability from the prominent Consumer Supported testing company in New Zealand found that 25% of the people they sampled had problems with generic cartridges compared with 6% of those who used same-brand cartridges.
In New Zealand we have strong protection laws, and the laws prohibit manufacturers from denying warranty claims if you use compatible consumables where the consumables were not likely the cause of the problem. You might want to look at your local laws and be guided somewhat by whether you have statutory protections.