How to choose
The first decision is whether you are willing to change editor. If not, an assistant that works inside your existing IDE removes the adoption problem entirely. If you are, a purpose built AI editor gives you whole repository context that plugins struggle to match.
Watch the billing model
Almost every product here now separates unlimited completions from metered agent credits. Two developers on the same plan can have very different bills.
Check what happens when the credits run out. Some stop, and some move you to usage based billing without a hard ceiling.
If your code cannot leave your infrastructure
Open weight models have closed most of the capability gap. A permissively licensed model you host yourself is now a serious option rather than a compromise, and it removes the review that a security team would otherwise have to run on a third party.