Ultimately, this comes down to personal preference and what works best for your needs. For example, a mesh feeder can work well for particular seed types, or if you prefer to use suet cakes for your birds - and it is much harder to find these in plastics. Metal options are also more likely to have perches for birds who prefer to perch. However, they're also much more likely to rust, dent, or degrade over time, while plastics will last.
Plastic options come with a higher risk of shattering if they are dropped or banged. However, they're also more likely to be squirrel-proof as they're harder to access by seed thieves! They also come with the benefit of being easy to clean and, often, simpler to assemble/disassemble.