I propose a hybrid answer, sourcing from the first two suggestions.

I think monero-wallet-gui would be the best tag for the official GUI, since it provides for basically a one-to-one correlation with monero-wallet-cli , both in the file name and the tag name.

I think third-party-wallets is a logical tag for all third-party wallets, whether GUI or not. I lean slightly in preference of spelling out third , rather than using 3rd . Then again, if the interest is in going short, then 3rd-party with no mention of wallets may be best.

I think specific tags for third-party wallets (such as jaxx ) are fine and useful, as long as there are several instances of a given tag. I think it's natural for this type of forum to require periodic housekeeping, so perhaps one-time- or two-time-use tags should be purged after six months or a year or whatever. (That is, to answer the 'threshold' question, I think two or three should be the threshold, but I think the tag should be able to be generated by users with enough rep, just as tags are created otherwise; and we'll just do periodic housekeeping to clean up the stale ones.)

I will also lastly point out that some suggestions here may appear better than other partly due to the timescale involved. For example, in the future there may be value in using tags to distinguish community-funded and/or core dev-reviewed 3rd-party wallets from 3rd-party wallets that did not go through those channels. It's unclear to me exactly how much this line of thinking should weigh on the current discussion.