First question to ask yourself, what's your budget limit?
Next, what's the maximum capacity you require?
If you're happy with a 20 - 25 lb capacity I'd suggest the 025. It handles 14"x18" racks which are essential for full slabs of ribs, and whole packer briskets. It also has a 300 o high heat limit. The 009 has 14" x 14" racks and a heat limit of 250. The different in cost ($161) is well worth the difference in my opinion.
The 045 will give you 10 lbs additional capacity + a temp probe to monitor meat temps. You can easily use a Polder digital thermometer to replace the CS probe so it really boils down to difference in capacity. The difference in price vs the 025 is $500. Does the extra capacity warrant the cost? That's something you need to determine.
The Amerique 066 provides 50 lbs of capacity. The control board provides the hold feature. You're also paying almost $1,000 more vs the 025 for the hold option + the extra 25 lb capacity.
If you're looking for a well built, basic smoker I'd go with the 025. As mentioned, additional features/capacity vs budget limit is something you need to decide for yourself. Performance and reliability are a given no matter which smoker you decide upon.