The smallest unit Kalinka-Ice has a 1/6 HP compressor. It is designed for runs up to 25 feet, and is a great choice for small bars, or for use with ice towers.
The 4 Tayfun units with 3/8 HP compressor are excellent mid-range glycol units, suitable for most bars. They are essentially the same unit, with choices between two different pumps, and vertical or horizontal orientation. The pump choices are either Procon (vertical or horizontal) or Totton (vertical or horizontal), giving 125 feet or 75 feet maximum run length. Horizontal or vertical orientation simply means the shape of the unit: having the choice between the two can help with installing the glycol chiller in tight spaces.
G30 Polar is close to the performance of the Tayfun units, with the main difference being the closed glycol system. It is great in hot, humid tropical conditions, where condensation water could otherwise dilute the water/glycol mix. With sealed unit the condensation water stays out of the glycol, and the glycol solution doesn't have to be changed so often. This saves you time and money!
LCB3500: Unlike other units, instead of a coil this quick glycol chiller has a cold plate. Running the glycol over the cold plate cools it down faster, allowing for a much smaller size glycol bath (2 gallons). This can again help save money on glycol. LCB3500 is good for runs up to 200 feet.
For longer than 200 feet runs, you need the best performance available. For that, there are the Extra units: EG-1/2P and EG-3/4P, with 1/2 HP and 3/4 HP compressors. Both have the option for 2 Procon pumps, which can be beneficial in a couple of different situations. First of all, if you have two different serving stations (beer towers), you can run both with just one glycol unit. The second situation where you might need two pumps is if you have a lot of products in one tower: one pump might not be able to keep the temperatures cool enough, especially if the run is long. EG-1/2P allows for a maximum of 250 feet runs, while EG-3/4P can do up to 450 feet runs.