XenForo System Requirements
- PHP: 5.6.0+ (PHP 7.2.0+ recommended)
- MySQL: 5.5+ (MariaDB / Percona also compatible)
- PHP extensions: MySQLi, GD (with JPEG support), PCRE, cURL, SPL, SimpleXML, DOM, JSON, iconv, ctype
- Common PHP functions must not be disabled
Eh, loads of hosts should have this sort of stuff.
I would actually argue that XenForo should use something a little less antiquated than PHP, but even in PHP Land, PHP 5.6 is EOL (end of life), so these requirements are actually a little too lax and leaves you open to potential security risks.
7 and it's ilk are the only versions with security updates still being released, to my knowledge.
And a VPS is usually the best case scenario all-round, as you run into all sorts of annoying little problems like having your site hacked and a phishing page hidden away somewhere, and then, getting terminated by your host randomly and unexpectedly for it.
SMTP is generally best practice, as PHP's mail() function relies on /usr/sbin/sendmail which is not only platform specific, but can be a bit slow and tends to be thrown in junk folders at major email providers.