SMS24me wins on because it doesn't gatekeep numbers behind a specific ecosystem. You aren't forced to use their app exclusively; you can configure the number to forward SMS to your email, webhook, or even a Telegram bot.
SMS24me Update: Your number is now fully portable. Transfer to any carrier or keep as permanent virtual line. Action required within 7 days. Reply KEEP to retain history. sms24me new numbers portable
It is free, requires no registration, and keeps your real phone number private. SMS24me wins on because it doesn't gatekeep numbers