having tried just about every method listed here, my preference is for the Jobo with Expert drums. All of the other multi-sheet processing methods leave something to be desired.
Yankee Tanks are still available I believe, but I don't use mine anymore even though it will do up to 12 sheets at a time. Because of the design of the sheet rack, it is quite possible to get developer surge near the edges of the frame. This may not be a problem when you're enlarging, since between the negative carrier masking some of the edge and the contrast response of silver-based enlarging paper, much of the localized over-development won't show, or can be cropped out. If you want to make contact prints, with alternative processes, or on AZO, however, you're SOL.
CombiPlan tanks may have the same problem- I can't really tell, because mine always leaked from the drain valve. It was too expensive to go out and replace it, with the possibility of getting another leaky one.
Trays- they're great if you're on a budget. There's no problem with developer surge, but they are the most prone to scratching of any developing method. The other downside of trays is that you have to get your hands in the chemicals (Wear gloves!), and then you have the largest surface area of exposed chemistry of any method around which you have to work. This method is most likely to stain clothes and/or burn nasal membranes from the fumes.
Sloshers are a multi-frame insert that sits in a tray and lets you gently agitate four or more sheets of film at a time. They reduce the amount of contact you have to have with your chemistry versus a straight up open tray, and they keep each sheet separate, reducing the chances of scratching. See trays for more downsides.
old Bakelite/hard rubber tanks have the advantage of being able to process large amounts of film at one time. If you can get the hang of working with stainless steel hangers, this can be a good way to go. However, until you get good at working the hangers, they will be prone to developer surge around the edges like the Yankee tank is. If you are doing some kind of stand, semi-stand or EMA development, this is the way to go. I keep a set of tanks and hangers around for when I want to do EMA development with 8x10 film. They also require a LOT of chemistry- an 8x10 tank takes over a gallon of developer. If you are using a pyro type developer or other developer that oxidizes rapidly, you are looking at 1 or at most 2 uses of that batch before you have to dump it, which is not good if you only have small batches to process.
Unicolor drums are a pain to fill, and the unicolor drum base only has one rotation speed, which seems best suited for doing color print development. They also do not have any good method for temperature control if you are processing on a unicolor motor base.
The Jobo expert drums allow you to use a reduced amount of chemistry, keep each sheet well separated, and provide very even development. The downside, other than expense, is the size. Expert drums are not small. They can be hand-rolled in a sink or on a counter, because the lids are designed well and dont protrude unevenly.