First there is obviously a big potential for spoilers here so be careful and those who reply try and be nice for those that come afterwards, my personal replies will be spoiler encased and should not spoil too much of anything.
Also the endings need not reflect on the quality of the show in general, two of my favourite pieces of entertainment on any medium are here under worst.
Here is my effort, no order intended and far from a complete list.
Best:
Regenesis. Canadian show, dare I say police procedural, about a group of scientists who help prevent science gone wrong.
Avatar the Last Airbender. US cartoon with very obvious anime/eastern mythos influences about a boy who is unfrozen following a war where the "world" is conquered.
Dead like me, dark comedy about a group of grim reapers (they appear in human form).
Sons of Anarchy, show about a group of bikers and their activities (illegal and otherwise). Owes more than a passing nod to the Hell's Angels (some of the lines in the series read like a direct quote from some of Otto Friedli's writings and interestingly I quite like it (patch wearing clubs are generally not something I go a bundle on). It is not finished yet but mentioned only as to my mind the first series finished leaving me wanting more, not through gimmick or some sense of "loyalty" (trying to think of better word, something along the lines of "I might as well stick this out") but through shear curiosity. It is very rare such a thing happens for me.
Worst:
The wire, on the face of it The Wire is s police show but if you watch it from the start it becomes a show with the police as main characters but lots more in between. Quite possibly my favourite show ever, my main gripe is it has raised the bar a bit high for my liking.
NCIS Another police show, the series has not ended but the people responsible get a two fingers up from me for the cliffhangers they always end each series with. While they are not quite as quickly undone as some other shows they are usually undone to some extent in the following series.
Burn notice Also still going on but it is a show about a spy forced into a retirement of sorts under false accusations and his subsequent investigation into said accusations and how he funds such things. See gripes about NCIS above although rather nicely this last series lacked it (aside from the mid series break).
Stargate (either version) Both are shows about a covert US air force group/similar exploring other planets. The last few series were odd if only because nobody knew when it was going to finish, for me this made it suffer as did the increasingly silly science backing it. Ultimately a few films have been made though.
The Shield. Another of my favourite shows and it is similar in concept to the wire although this time focusing on a corrupt (but nicely so) cop and his team in LA. Nicely some of the plotlines were tied up/revisited earlier rather than in the final glut many other shows get.
Also the endings need not reflect on the quality of the show in general, two of my favourite pieces of entertainment on any medium are here under worst.
Here is my effort, no order intended and far from a complete list.
Best:
Regenesis. Canadian show, dare I say police procedural, about a group of scientists who help prevent science gone wrong.
The end show is set a few decades later and shows a "court case" where the principal cast or relations attempting to defend/explain the consequences of their actions in the final plot arc.
Avatar the Last Airbender. US cartoon with very obvious anime/eastern mythos influences about a boy who is unfrozen following a war where the "world" is conquered.
Obviously a martial arts type program needs a battle to finish it off. Some would have also argued that finishing where they did (four classical elements, each series (called books) named for said elements) and indeed I might have felt the same way going into it. Depending upon who you speak to it was a TV film as an ending (in reality it was the usual here are the last few episodes), having multiple battles occurring (multiple groups of characters) was always going to be
Dead like me, dark comedy about a group of grim reapers (they appear in human form).
Actually comes as film set a few years after the series ended, some have slated the film but I enjoyed it if only for the reversal of roles that was going on and how it explored some more of the mythos it created.
Sons of Anarchy, show about a group of bikers and their activities (illegal and otherwise). Owes more than a passing nod to the Hell's Angels (some of the lines in the series read like a direct quote from some of Otto Friedli's writings and interestingly I quite like it (patch wearing clubs are generally not something I go a bundle on). It is not finished yet but mentioned only as to my mind the first series finished leaving me wanting more, not through gimmick or some sense of "loyalty" (trying to think of better word, something along the lines of "I might as well stick this out") but through shear curiosity. It is very rare such a thing happens for me.
Worst:
The wire, on the face of it The Wire is s police show but if you watch it from the start it becomes a show with the police as main characters but lots more in between. Quite possibly my favourite show ever, my main gripe is it has raised the bar a bit high for my liking.
The show was cut short by the network (HBO) and to my mind it suffered for it. While it was not flashbacks (the only flashbacks as such are the interludes between series 4 and 5 showing some backstory which I suggest people get, I found them on youtube) it was cutaway showing where most of the surviving characters found themselves at the end of the series. While that was OK I thought the last plotline (which was a really good idea) was cut far short and suffered for it.
NCIS Another police show, the series has not ended but the people responsible get a two fingers up from me for the cliffhangers they always end each series with. While they are not quite as quickly undone as some other shows they are usually undone to some extent in the following series.
Burn notice Also still going on but it is a show about a spy forced into a retirement of sorts under false accusations and his subsequent investigation into said accusations and how he funds such things. See gripes about NCIS above although rather nicely this last series lacked it (aside from the mid series break).
Stargate (either version) Both are shows about a covert US air force group/similar exploring other planets. The last few series were odd if only because nobody knew when it was going to finish, for me this made it suffer as did the increasingly silly science backing it. Ultimately a few films have been made though.
The Shield. Another of my favourite shows and it is similar in concept to the wire although this time focusing on a corrupt (but nicely so) cop and his team in LA. Nicely some of the plotlines were tied up/revisited earlier rather than in the final glut many other shows get.
All the crimes have their consequences it seems and the last series (or at least the last two thirds) deal with the various people getting out of trouble or not as the case may be. It felt a bit rushed to me and almost needlessly so (there seemed to be a fair bit of filler earlier on). This may change when I rewatch the final series in one sitting rather than on a week by week basis.