On the subject of pipe filters there is much debate and the arguments can ofttimes devolve into dottle slinging contests of absurdity so I felt I should add my own opinion on the subject into the fray and try to be objective as possible. My background with smoking pipes with filters is varied and I lean towards the "like" side of the equation where I am most likely to be found in a room with my lonely echoing footfalls as my only company but I digress, on with the the show.
My personal experience with filtered pipes comes down to 5 brands: Frank, Savinelli, Brigham, Dr Grabow/Medico, and Kaywoodie. Each has their own distinct pros and cons and in my opinion there is no one type that is better than the others, it's simply a matter of personal taste.
Frank: The 2 Frank pipes I have date from around 1923 and were Ebay Finds. One is a Frank Tidewater straight apple shape and the other is a small Dublin often called a "University" pipe as it was ment to make for a quick smoke between classes. Both have the earliest and simplest type of filter, a metal tube though the lower stem that fits into the shank called a condenser. This tube helps to condense out excess moisture from the smoke, helping to keep tongue bite at a minimum. My opionin is that it does this and rather well but all that moisture has to go somewhere and it ends up in the lower shank making the pipe gurgle. Fortunately it's easy to insert a pipe cleaner through the stem to the bowl and wick up this moisture but having to do it multiple times per smoke can be tedious. Since the "filter" is built in, there is nothing to replace and pipe cleaner with some 151 rum cleans out any accumulated gunk easily. Couple this with briar that has aged for 90+ years and these pipes have become absolute favorites of mine. Once I said "The pipe chooses the tobacco" and thie is true as these pipes favor burleys and cavendish tobacco.
Kaywoodie: Kaywoodie has to be the most recognizeable pipe manufacturer next to Dr Grabow and their "stinger" design of pipe filter the most controversial. I've owned several Kaywoodies and I found to a one the only smoke burley tobacco well and since I only smoke burley occasionally I ended up selling off all the ones I owned. The stinger screws together the shank and the stem with a metal fitment and unlike other pipes that cannot be disassembled when hot, Kaywoodies can be unscrewed. The reason for this is panfully obvious as you start to smoke one and even with tobacco as dry as the Sahara sands you soon get enough gurgle to think you are smoking a hookah. Hence the pipe was made to be taken apart and the stinger wiped of moisture whilst smoking. The fact that a pipe cleaner cannot be passed down to the bowl through the stem because of the stinger was enough to make most people cut the stinger off completely which is the condition you find many Kaywoodies in on Ebay. In my personal experiece I found the kaywoodie system interesting but as I mentioned I didn't smoke enough burleys to warrant keeping them. Couple that with the fact I kept wiping off the stinger with my pocket handkercheif which then lent a not so wonderful mundungus aroma to my pocket I was done with kaywoodies even though the briar on the older models is of rather good quality.
Dr Grabow: Dr Grabow's original pipes utilized a very simple stinger design but sometime in the 60's(?) they switched to using a paper filter. This marks the first time that a pipe had an actual filter that the smoke had to pass through as opposed to around. Many people will tell you that the paper lends a flavor to the smoke, perhaps but not enough to get excited about in my opinion. The filter actually is rather good at wicking moisture from the smoke and keeping it in the filter and the Dr. Grabow I used to have (it broke in my baggage flying back to the Philippines in 2009) I never remember having to deal with pipe gurgle. It was an older model from the 60's and was made of decent briar and smoked a wide variety of tobaccos well. I rather mourned the loss of that pipe. One thing I found out by playing around is that with a little trimming and fiddling the 6mm savinelli balsa filters will fit in a Dr Grabow and are an improvement on the paper filters as they smoke once and get thrown away but the Savinelli filters are good for a weeks worth of smoking (for me). I intend to aquire some more Dr. Grabows in the future, but the older ones from the 60's or so not the new ones where the workmanship has declined.
Savinelli: I own 3 Savinell pipes, a Bing's Favorite Rusticated, a Trevi Billiard and an Iwan Ries stamped bent billiard made for them by Savinelli. All take the 6mm Balsa wood filter or a restricting adapter that eliminates the need for a filter. In this case the smoke passes around and not through the balsa which wicks out moisture and virtually eliminates tongue bite. Hands down, Savinelli is my favorite pipe maker and having smoked my Savinelli's hundreds of times with a variety of tobacco over the years I have NEVER had a pipe gurgle on me once. The flipside to this is having to purchase the balsa filters as each time you smoke you will have to let the pipe cool and remove the filter so it can dry. I get about 3-4 smokes from a filter (a week for me) before I toss it, clean and sweeten the pipe and insert a new filter. I have little to comment on the taste issue of the balsa except tha by slightly cooling the smoke and reducing the moisture, the flavor of the tobacco really comes through. This is a bonus when smoking rather lightly flavored tobacco like Grousemoor, Skiff Mixture, or Presbyterian Mixture. The only other downside is that you cannot pass a pipe cleaner to the bowl with the filter in place but since you needn't worry about gurgle it's not really an issue to me.
Brigham: Brigham is a Canadian company making pipes and I honestly didn't know about them until fairly recently in my pipe smoking career. Their take on the whole filter idea is the most novel as it's a hybridization of the Frank type condensor with the Savinelli filters except that Brigham makes theirs of rock maple. The smoke has contact with the rock maple filter for a long time as it travels up the stem which wicks away alot of moisture that would lead to tongue bite but since it doesn't expend into the shank like a Savinelli balsa filter you will get pipe gurgle. No problem though as the rock maple filter in a hollow tube and passes a pipe cleaner to the bottom of the bowl with minimum effort. I only own one Brigham pipe but it has become a favorite of mine and is dedicated to latakia English tobaccos. The rock maple filters can be washed with hot water and dried out making them last the longest of any filter on the market. According to Brigham you should replace it every 2-3 weeks which means you get between 10-15 smokes out of it. Since I dedicate pipes to a particular type of tobacco I could probably get a month to month and a half out of the filter and I've read a couple of reports that some people never change the filter. One constant on all the anecdotal evidence is that Brigham, more than any other pipe with a filter, has the smallest percentage of people smoking it without the filter. Brigham pipes are affordable and come in several "grades" which is misleading as the same superior quality briar goes into the "low end" pipes as the "high end" pipes the only difference being the finish.
I hope that I have unmuddied the water a bit when it comes to pipe filters. Essentially they are selling points used by manufacturers to make their brand "better" than others and of course eliminate the twin bugaboos of Pipe Gurgle and Tongue Bite, both of which can be reduced with proper moderation of puffing and tobacco moisture.