I've been thinking about rules and rulesets in go.
A plurality of rulesets is unfortunate, in that it significant complicates the problem, giving several targets to aim for when building a computer go player. Fortunately few, if any, computer go players are sufficiently advanced for differences between rulesets to become a significant factor. Also, the fact that there are several rulesets potential gives computer go researchers and others choices about which rulesets to use.
Many computer go players choose to ignore certain rules, including avoid capture by seki and even ko. Noting but not modelling certain aspects of the problem is of course a classic feature of decomposition-based problem solving styles used in computer science and mathematics (and one which I'm sure my system will eventually have, once I have a system to have such features).
Personally I'm a fan of the New Zealand rules, because: (a) they're clearly stated; (b) they are stated in a way that suits my current purposes (i.e. in a mathematical way); (c) they don't have exceptions; (d) they don't have a history of change and (e) they are widely and correctly understood (perhaps largely because of the previous reasons). On the other hand, they exist in a cultural wasteland, there is a dearth of pro-level games on record using the New Zealand ruleset and none of the "famous" games have been played using them. This is not a serious issue, of course, if one is learning oneself, but if one is building a computer go player there are a number of uses for a larger corpus of pro-level games---pattern extraction, statistical comparisons and finding example end-games. It is also less of an issue if one is evolving (or proving) a system from first principals.
The New Zealand ruleset: http://homepages.ihug.co.nz/~barryp/rules.htm