One negative point I have experienced with Parker pens is that they only seem to take Parker cartridges which are not as widely available as you would expect and cost a lot more than own brands.
Is this the case with other brands?
Our local store stocks the refills by the dozens and then some when the 'I must have the right pencil-case' shopping starts in earnest in late August!!
Depending on where and when you purchase them, you can stock up on PQ refills at less than 21p @(average 27p@). For the prolific writer, you can buy in packs of 15. Lamy's costs about 37p-39p@.
WHSmith has a cartridge pen at around Â£3.50 but I don't know how much their refills are as we were seduced by the free pen engraving offered for Parker pens at the time of our purchase. Some styles have a rubber grip for comfort. No left or right versions though but most brands do a washable ink (black or blue) and that is what is most important if you have no other concerns about handwriting grips etc.
Hope it is permissible to mention these products.