seannymurrs, I think there is no such a thing as a "best setup". It all depends on your needs, requirements and intended usage. First, different categories (baths, immersion circulators, and external controllers) offer different options in terms of versatility, safety, precision, integration of parts, or mobility. Then each specific brand and model within a same category have specific implementation details to value or worry about.
I own 3 units, representing each of the categories: a water bath (SousVideSupreme Demi), a circulator (Addèlice SWID) and a controller with in-water heater and bubbler (eiPOT). I like all three, and can not recommend one or the other, it all depends on your needs.
SVS Demi is self-contained, you don't have to worry about getting a properly insulated container or start cutting lids with special saws, which is very convenient. It also has the look of a standard kitchen appliance which helps with acceptance. But the fixed pot size and integration of parts make it less mobile, less versatile, and require permanent countertop space. Having the thermometer and heater out of the water and using natural convection make it less precise, slower for short cooking times, and requires being more careful with bags positioning, but also make it easier to clean and require less maintenance. It is not very powerful: long heating times and does not perform very well with temperatures between 85 and 90ºC. No safety mechanisms for things like low water level.
SVS It is my default choice for long cooking times (tough meats), because it is properly insulated from scratch, it is totally noise-free, for those cookings absolute precision and water circulation became less important, and if electricity goes off for a second the cooking process goes on when it comes back. The latter is not the case with the other models, which means that if you have a short outage while sleeping or not at home you will likely have to throw the food to the garbage.
Addélice SWID offers all the versality of a circulator, it efficiently circulates the water and controls temperature with much better precision that SVS. Also has more safety mechanisms, like controlling the water level. It's not big and can be easily stored on a cabinet or taken with me to parties or when going on holidays. Detects automatically the pot size and insulation and adjust to them without any hassle. Very powerful, heats the water 3 times faster than the Demi and allows pots of very different sizes up to almost 50 liters. The aspect on the countertop starts to look strange, you have to search adequate recipients and lids and maybe insulate them yourself, and is a little noisier than SVS (though not much). Also requires some more cleaning and maintenance (I really like that in this model cleaning does not require unscrewing plastic parts like Polyscience and others). Circulators take a good part of the useful water volume of your recipient, and make it harder to adapt lids to properly cover different baths to limit evaporation. SWID has an extremelly useful timer up feature that most other models do not implement: by default it will show cooking time if you don't program a specific time, and if you define a cooking time it goes down to zero then a led (and alarm) signals finishing and the timer starts going up and shows you the additional time the food has been cooking.
SWID is my default choice for shorter cooking times, especially if they require precision, and when I want to rapidly adapt to using different baths. Also if I need to prepare a lot of food for parties and the like.
An external controller offers maximum versatility, and if combined with a submersion heater like the FMM II (eiPOT) it is an excellent alternative to a circulator. It not only adapts to different bath sizes like the circulator but also to different heaters. This comes at a cost, though, and autotuning can be pretty slow when changing baths or require expert knowledge to figure out the best parameters. Your kitchen will start to have the "mad scientist" look, which your partner may not like... and the positioning of the controller above the water bath if you require bubbles with the FMM is cumbersome at times, you may not be able to position it like that in the place where you would like to have the bath. On the other hand the small profile of the cables of the FMM make it great for any pot or bath without removing useful space, and with a beer cooler you have a cheap perfectly insulated bath with lid from day 1. It is very powerful and can heat big baths, only the baths must have different geometry (tall and narrow) than big baths for a circulator (low and wide). You can tune many parameters and options in the controller, which can offer hours of wonder if you are of the geek type...
eiPOT is my default option to travel and take to parties (the beer cooler doubles function to move the food to the party, then as the cooking vessel, and the eiPOT is the lightest unit), for cooking eggs (offers the required speed & precision and the forced bubbles from bottom to top do not move the eggs around like the circulator does), or for short cooking times in soup-type pots.
As you see, no clear winner. You have to match the unit to your needs.
