Thailand visa exemption vs tourist visa, which should I get for a 7 week trip?

Planning to spend about 7 weeks in Thailand. I know the visa exemption only covers 30 days. Should I apply for a proper tourist visa before I travel, or enter on the exemption and extend once I’m there?

I think it depends on your nationality. I’m from the US and I just had to fill out some entry form online a few days before my trip and didn’t have to even bother with a visa